9. A car driver brakes gently. Her car slows down front --
deceleration?
10. A train slows down from 60m/s to 20m/s in 50s.
a) What is its acceleration?
b) Write your answer in words?
11. The acceleration of car is 10m/s. If the car starts from rest,
a) What will be its speed after 10s?
b) How long it takes to reach a speed 1000m/s?
12. A sprinter has an acceleration of 5m's during the first 2 seconds of the race. What
velocity does she reach after this time?
13. A train increases its velocity from 6m/s to 10m/s. Calculate its acceleration?
14. A car travelling at 20m/s slows down to 10m/s in 25. Calculate its acceleration?
15. Leaving bus stop, the bus reaches a speed of 8m/s after 10s. What is its acceleration?

Answers

Answer 1

Answer:

9) This is a case of deceleration

10)-0.8 ms-2

b) acceleration is the change in velocity with time

11)

a) 100 ms-1

b) 100 seconds

12) 10ms-1

13) more information is needed to answer the question

14) - 0.4 ms^-2

15) 0.8 ms^-2

Explanation:

The deceleration is;

v-u/t

v= final velocity

u= initial velocity

t= time taken

20-60/50 =- 40/50= -0.8 ms-2

11)

Since it starts from rest, u=0 hence

v= u + at

v= 10 ×10

v= 100 ms-1

b)

v= u + at but u=0

1000 = 10 t

t= 1000/10

t= 100 seconds

12) since the sprinter must have started from rest, u= 0

v= u + at

v= 5 × 2

v= 10ms-1

14)

v- u/t

10 - 20/ 25

10/25

=- 0.4 ms^-2

15)

a=v-u/t

From rest, u=0

8 - 0/10

a= 8/10

a= 0.8 ms^-2


Related Questions

A jogger runs 186 meters westward, then 210 meters eastward, then 156 meters westward, and finally 8A meters eastward.​

Answers

Answer:

48

Explanation:

Given that a jogger runs 186 meters westward, then 210 meters eastward, then 156 meters westward, and finally 8A meters eastward.

To calculate the displacement, let assume that the

Westward = positive

Eastward = negative

Displacement = 186 - 210 + 156 - 84

Displacement = 342 - 294

Displacement = 48 m

Since the answer is positive, the direction of the displacement will be westward.

A cross-country skier moves 36 meters eastward, then 44
meters westward, and finally 22 meters eastward.Whats the Magnitude and Direction?

Answers

Answer:

Magnitude = 14 metres

Direction = eastward.

Explanation:

A cross-country skier moves 36 meters eastward, then 44meters westward, and finally 22 meters eastward.

Whats the Magnitude and Direction?

The magnitude and direction will be the displacement of the cross country skier.

Let the east ward be positive and the west ward be negative.

Since the skier moves 36 meters eastward, then 44meters westward, and finally 22 meters eastward. Then, that will be:

36 - 44 + 22 = 14

Since the answer is positive, the magnitude is 14 and the direction is east ward.

What is a terrestrial planet?

Answers

Answer: Hi!

A terrestrial planet is composed of a solid substance like rock or earth. A few examples are our planet, Earth, and the red planet, Mars. These are the planets that are the closest to the sun. There are four terrestrial planets in total. The only known terrestrial planet that has life, however, is our own, Earth! Earth has the perfect conditions for supporting life forms.

Hope this helps!

Answer:

Jupiter

Explanation:

question : Which planet is terrestrial?

Jupiter

Mars

Saturn

Uranus

Mr.Hernandez has 1,127student photos to display around the halls of the school. He plans to put them on 49 poster boards with the same number of photos on each board how many student photos will Mr. Hernandez place on each poster board

Answers

Answer:

23 student photos

Explanation:

All you have to do is divide 1,127 by 49. So take the photos and fill each poster board. There will be no photos left! Hope this helps!

Uma chapa metálica, com um furo central de diâmetro "d", é aquecida dentro de um forno. Com o aumento da temperatura, podemos afirmar: Tanto a chapa quanto o furo permanecem com as mesmas dimensões. O furo permanece constante, e a chapa aumenta a sua dimensão. O furo diminui enquanto a chapa aumenta a sua dimensão. Tanto o furo quanto a chapa aumentam as suas dimensões. O furo diminui enquanto a dimensão da chapa permanece constante.

Answers

Answer:  O furo diminui enquanto a chapa aumenta a sua dimensão.

(The diameter decreases and the dimensions of the metal increases)

Explanation:

I will answer in English:

Here we have a piece of metal with a small hole on it, that is heated in a hoven.

We know that when a piece of metal is heated, it will expand (the density decreases, so the dimensions of the piece of metal increase).

Now, particularly, the hole will also expand but inwards, as each "extreme" of the piece of metal, will expand into where it has less resistance, so it will expand in the region where there is no material. This "inwards" expansion is why the diameter of the hole will decrease.

1500 + 30.4 = ? Use the correct number of significant figures. plz plz help me

Answers

Answer:

1530.4?

Explanation:

1500.0

+030.4

1530.4

If friction is ignored and the ball is dropped, it experiences a gain in ____ and a decrease in ___. Question 8 options: kinetic energy; potential energy potential energy; kinetic energy thermal energy; potential energy potential energy; thermal energy

Answers

Answer:

My answer is when the ball is going it experience kinetic energy which is the energy of a moving object while when the ball has stopped then it will have potential energy which means it's at rest so for the ball not to experience friction then there is a gain in kinetic energy and decrease in potential energy.

Answer:

Gain in Kinetic energy and decrease in Potential energy.

Explanation:

What is kinetic energy ?

The energy possessed to a body due to its motion is called kinetic energy.

K = [tex]\frac{1}{2} .m.v^{2}[/tex]

What is potential energy ?

The energy possessed to a body due to its position is called potential energy.

[tex]U =mgh[/tex]

As the falls , due to pull of the Earth its velocity increase thus its kinetic energy also increases .As it falls , its height decrease from the Earth thus potential energy decrease.

Hence in free fall , the ball experiences gain in kinetic energy and decrease in potential energy.

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what is the displacement if you walk 100m north, then 200m south, then 300m north ​

Answers

Answer:

200 m North

Explanation:

1. Let's represent north as positive and south as negative.

       (100 m)+(-200 m)+(300 m)

                                = 200 m

2. Since the answer is positive, the units are 100 m NORTH since north represents positive.

A car accelerates from rest at 5.75m/s2 for 4.4 sec when it runs out of pavement and runs into some mud. In the mud it accelerates to rest at -5.5m/s2. How far did it move from the beginning to the end? Give a variable legend for this problem. The model for this problem?

Answers

Answer:

113.85 m

Explanation:

When the car is on the pavement:

v₀ = 0 m/s

a = 5.75 m/s²

t = 4.4 s

Find: Δx and v

Δx = v₀ t + ½ at²

Δx = (0 m/s) (4.4 s) + ½ (5.75 m/s²) (4.4 s)²

Δx = 55.66 m

v = at + v₀

v = (5.75 m/s²) (4.4 s) + 0 m/s

v = 25.3 m/s

When the car is in the mud:

v₀ = 25.3 m/s

v = 0 m/s

a = -5.5 m/s²

Find: Δx

v² = v₀² + 2aΔx

(0 m/s)² = (25.3 m/s)² + 2 (-5.5 m/s²) Δx

Δx = 58.19 m

The total displacement is therefore:

55.66 m + 58.19 m = 113.85 m

Which statement is true about acceleration?
Ο Α.
It is the rate of change of speed per unit time.
B.
It is the rate of change of displacement per unit time.
O C.
It is the rate of change of velocity per unit time.
O D.
It is the rate of change of position per unit time.

Answers

Answer

A

Explanation:

It is the rate of change of speed per unit time

Which is directly proportional to your weight on a planet's surface?

Answers

Answer:

Weight is directly proportional to our mass and acceleration due to gravity of that planet

Answer:

Your mass and the mass of the planet

Boston Red Sox pitcher Roger Clemens could routinely throw a fastball at a horizontal
speed of 119.7 m/s. How long did the ball take to reach home plate 17.3 m away?

Answers

Answer: 0.145 seconds

Explanation:

Given that Roger Clemens could routinely throw a fastball at a horizontal speed of 119.7 m/s. How long did the ball take to reach home plate 17.3 m away

Since the speed is horizontal

Using the formula for speed which is

Speed = distance/time

Where

Speed = 119.7 m/s

Distance covered = 17.3 m

Time is what we are looking for

Substitute all the parameters into the formula

119.7 = 17.3/ time

Make time the subject of formula

Time = 17.3 / 119.7

Time = 0.145 seconds.

Therefore, it will take 0.145 seconds to reach the home plates

A 0.40 kilogram bird is flying at a constant speed of 8.0 m/s. What is the bird's kinetic
energy?

Answers

Answer:

12.8 J

Explanation:

Kinetic Energy: This can be defined as the energy posses by a body due to its motion. The S.I unit of kinetic energy is Joules(J)

From the question,

Ek = (1/2)mv²........................... Equation 1

Where m = mass of the bird, v = speed of the bird.

Given: m = 0.40 kg, v = 8.0 m/s.

substitute these values into equation 1 above,

Ek = 1/2(0.4)(8²)

Ek = 0.2(64)

Ek = 12.8 J

A scientist heats a piece of iron until it is glowing white–hot. He places the metal inside a metal box. He removes all of the air from the inside of the box. After a few seconds, the sides of the box that are not touching the metal begin to feel warm. Which process is most likely responsible for the warming?

Convection
Convection current
Radiation
Evaporation

Answers

Answer:

The answer is Radiation.

Explaination:

A and B are wrong because you can't have convection or convection currents without air, and all the air has been removed from the box.

D is wrong because there is no liquid in the box.

C is correct because heat can be transmitted even through a vacuum by radiation (e.g., the Sun). You can quickly feel the heat radiated by a piece of white-hot iron.

Explain how skeletal muscles and nerves work together to help you move

Answers

Sensors in the muscles and joints send messages back through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it's in

ii) The distance travelled by an object in time
(100 + 1) s is (5.2 + 0.1) m. What is the
speed and it's error?
Ans: 0.052 ms-l, + 0.029 ms'​

Answers

Answer:

  v = (5.2 ± 0.2) 10⁻²   m / s

Explanation:

This is an exercise in kinematics of uniform motion. The formula for the average speed is

          v = x / t

let's calculate

          v = 5.2 / 100

          v = 0.052 m / s

          v = 5.2 10-2 m / s

we have to find the uncertainty of this quantity we propagate the error using derivatives

          Δv = dv /dx   Δx + dv /dt   Δt

taking everything in the most unfavorable case, I mean all positive

let's make the derivatives

          dv / dx = 1 / t

          dv / dt = -x / t²

we substitute

         Δv = 1 /t  Δx + x /t²   Δt

let's calculate the error

        Δv = 1/100 0.1 + 5.2 / 100²  1

        Δv = 1 10⁻³ + 5.2 10⁻⁴

        Δv = 1.52 10⁻³ m/s

           

the error must be given with a significant figure

         Dv = 2 10⁻³ m / s

the answer is

         v = (5.2 ± 0.2) 10⁻²   m / s

!!PLEASE HELP ME!!
if you were to fill a graduated cylinder to 250 mL then drop an object in that raises the water level to 300 mL, what is the volume of the object, in cubic centimeters?

Answers

50cc. The conversion rate is 1ml to 1cc so you simply subtract the level in the cylinder before the object (250ml) from the level after dropping in the object (300ml) to find the difference, or the change. And then you multiply that figure by a factor of one because 1ml is equal to 1cc.

Un objeto se mueve con una rapidez constante de 8 m/s. Esto significa que el objeto: a) Aumenta su rapidez en 8m/s cada segundo b) Disminuye su rapidez en 8m/s cada segundo c) No se mueve d) Tiene aceleracion positiva e) se mueve 800 cm cada segundo

Answers

Explanation:

Constant speed means that the object is covering equal distance in equal interval of time. The motion is called uniform motion for such case. In this problem, it is given that an object is moving with a constant speed of 8 m/s. It means that it does not change its speed. It is moving with a single speed constantly.

We can say that it moves 8 meters every second or 800 cm every second.

2
The graph represents the movement of a body.
10
speed
m/s
8
6
4
N
0-
0 1 2 3 4
time, s
How far has the body moved after 5s?
A 2 m
B 10 m
C 25 m
D 50m​

Answers

Answer:

D

Explanation:

it's the speed of the body I think

A boy rolls a toy car across a floor with a velocity of 3.21 m/s. How long does it take the car to travel a distance of 4.50 m?

Answers

Answer:

Time taken for the car to travel a distance of 4.50 m = 1.40 seconds

Explanation:

velocity of toy car = 3.21 m/s

distance travelled by toy car = 4.50 m

Time = ?

[tex]Velocity = \frac{Distance}{Time} \\Time =\frac{Distance}{Velocity}[/tex]

[tex]Time = \frac{4.50}{3.21} \\Time = 1.40s[/tex]

Therefore, the time taken for the car to travel a distance of 4.50 m = 1.40 seconds

The equation for distance is d = st i. If a car has a speed of 22.3 m/s and drives for 8.5 seconds, how far does it go? (1 point)

Answers

distance(d) = speed(s) × time (t)

= 22.3 × 8.5

= 189.55m

How much work is done (in L*atm) by a gas that expands from 7.6 liters to 24 liters against an external pressure of 3.4 atm?

Answers

Answer:

The work done by the gas is 55.76 L*atm.

Explanation:

The work can be found as follows:

[tex] W = p\Delta V = p(V_{f} - V_{i}) [/tex]     (1)

Where:

p: is the pressure = 3.4 atm

V(f): is the final volume = 24 L

V(i): is the initial volume = 7.6 L

By replacing the above values into equation (1) we have:

[tex]W = p(V_{f} - V_{i}) = 3.4 atm(24 L - 7.6 L) = 55.76 atm*L[/tex]  

Therefore, the work done by the gas is 55.76 L*atm.

I hope it helps you!

Which of the following is the correct equation we get
when we rearrange a = b *c so that c is by itself on the
right side of the equals sign?
Oa=c
O a + b = c
O a/buc
O a*b = c

Answers

Answer:

[tex]\frac{a}{b}=c[/tex] which agrees with the third answer in your list of answer options

Explanation:

Start with:

[tex]a=b\,*\,c[/tex]

divide both sides by b to isolate c on the right:

[tex]\frac{a}{b} =\frac{b\,*\,c}{b} \\\frac{a}{b} =c[/tex]

What kind of lens (converging or diverging) should he use to correct his eyesight, and what should be the focal length of the lens?

Answers

Incomplete question. However, I provided some information about when a converging or diverging lens is used. The common ones are:

Explanation:

In other to correct eyesight problems certain types of lenses are used depending on the condition.

Diverging lens: If the individual is suffering from nearsightedness (myopia); a condition that prevents a person from seeing distant objects clearly, but is able to see close objects clearly, then a divergent lens may be used to correct his eyesight.

Covergent lens: In a case where the person has a condition that prevents him from seeing close objects clearly while distant objects may be clear is called Farsightedness (hyperopia).

A snowball that will be used to build a snowman is at the top of a only hill. If the
potential energy of the snowball is 520 J and the mass of the snowball is 2.2 kg,
what is the height of the hill?

Answers

Answer:

h = 24.11 m

Explanation:

Given that,

The potential energy of the snowball is 520 J

The mass of the snowball is 2.2 kg

We need to find the height of the hill. The potential energy of an object is given by the formula as follows :

[tex]E=mgh[/tex]

g is acceleration due to gravity

h is height of the hill

[tex]h=\dfrac{E}{mg}\\\\h=\dfrac{520}{2.2\times 9.8}\\\\h=24.11\ m[/tex]

So, the height of the hill is 24.11 m.

in your own words provide two advantages of using meters as a measurement of length rather than old measurements of length such as hands or steps

Answers

Answer:

First, the meters is the unit used in almost all the world today.

Then using meters as your unit will be easier to read and interpret for a larger number of people than if you use an older system, like hands or steps.

And because of the fact that almost all the world uses the meter as the unit for length, almost all the equations and formulas are written in meters.

Precision: The meter is exactly defined as:

"The length of the path traveled by light in a vacuum in 1/299,792,458 of a second"

So the meter is an exact (and accepted) unit.

Then using this unit for measures of length also provides some " legitimacy" for you measure.

The answer answer it it la

Answers

Answer:

c) a tube light

Explanation:

a solar panel converts light energy into electricity

a tube light converts electricity into light

A coil of wire is connected to a galvanometer and the north end of a magnet moved towards the center of the coil causing the needle on the galvanometer to deflect. If the south pole of a magnet is moved away from the center of the coil the needle on the galvanometer would deflect in the same direction.

a. True
b. False

Answers

Answer:

a. True

Explanation:

In electromagnetic induction, the induced current always try to oppose the action that produces the induction (Lenz law). The approaching north end of the magnet will induce a current on the coil that will flow in an anticlockwise direction in the current (which induces a magnetism with the equivalent of a north pole of a magnet). The action of this induced current repels the magnet, in an effort to stop the motion that is producing the electromagnetic induction. When we also move the south pole of the magnet away from the coil, it induces an anticlockwise current in the coil, which tries to attract the south pole of the magnet so as to prevent it from moving. So both actions produce currents that flow in the same direction, which means that the needle of the galvanometer will deflect in the same direction.

Answer:

a. True

Explanation:

In electromagnetic induction, the induced current always try to oppose the action that produces the induction (Lenz law). The approaching north end of the magnet will induce a current on the coil that will flow in an anticlockwise direction in the current (which induces a magnetism with the equivalent of a north pole of a magnet). The action of this induced current repels the magnet, in an effort to stop the motion that is producing the electromagnetic induction. When we also move the south pole of the magnet away from the coil, it induces an anticlockwise current in the coil, which tries to attract the south pole of the magnet so as to prevent it from moving. So both actions produce currents that flow in the same direction, which means that the needle of the galvanometer will deflect in the same direction.

Imagine two planets, Planet A and Planet B, in a distant galaxy. Both planets have the same size but Planet A has more mass than Planet B. Two identical spacecrafts land on each of the planets. Which of the statements is true?

The weight of the spacecraft is greater on Planet A but the mass is the same on both planets
The mass of the spacecraft is greater on Planet A but the weight is the same on both planets
Both the mass and the weight are greater on Planet A.

Answers

Answer:

The weight of the spacecraft is greater on Planet A but the mass is same on both planets.

Mass is same on both planets because mass is always constant which means it doesn't change when place varies.Weight of the spacecraft is more in planet A because it has more value of acceleration due to gravity. (g=GM/R^2)

Thus the first statement is true

What is the dependent variable in an experiment testing the effects of pH on growth of a seed?

a
Seed growth
b
pH
c
Filter paper
d
Type of seed

Answers

The correct answer is A. Seed growth

Explanation:

Experiments often involve two main variables: the independent variable and the dependent variable. In an experiment, the dependent variable is always the main factor being studied; also, this is "dependent" because it is affected by other factors. In the case presented, the dependent variable is seed growth because this is the specific phenomenon that is being analyzed. Moreover, this factor is affected by the changes in pH. On the other hand, the pH, which is the second factor is the independent variable because this is not affected by the first variable and it is manipulated on purpose.

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