6d A boy pushes his little brother on a sled. The sled accelerates from rest to (4 m/s). If the combines of his brother and the sled is (40.0 kg) and (20 W) of power is developed, how long time does the boy push the sled?​

Answer:

Explanation:

We don't need the mass of the car in the equation to solve for final velocity, since the values given for the acceleration and the time it took to accelerate to that velocity are given. The equation we need is the one for acceleration, which is

[tex]a=\frac{v_f-v_0}{t}[/tex] We are solving for final velocity, we know the initial velocity is 0 (starting from rest), and the time to complete this acceleration (10 m/s/s) is 3 seconds:

[tex]10=\frac{v_f-0}{3}[/tex] which is the same thing as saying

[tex]10=\frac{v}{3}[/tex] so

v = 30 m/s

Answer:

Yes

Explanation:

The friction is bigger than the mechanical energy so it kind off takes over the mechanical energy. but if the friction decreases mechanical energy can work on the object again

Answer:

yes

Explanation:

The gases and dust particles thrown into the atmosphere during volcanic eruptions have influences on climate. ... Volcanoes have also caused global warming over millions of years during times in Earth's history when extreme amounts of volcanism occurred, releasing greenhouse gases into the atmosphere.

Answer:

So actually, it is not so much the distance at a particular time that affects the seasons. It is a common misconception. It is in-fact the earths tilt. When we rotate around the sun, due to our tilt, the North and South of earth have different seasons. This is because when light is shining on to earth, because of Earths tilt, on one half the light shines more directly and on the other it scatters thus the different temperatures, causing season. Hope this helps.

Answer:

The magnitude of the force acting on the sled is 60.5 newtons.

Explanation:

The Work-Energy Theorem states that the work done by the external force applied on the sled ([tex]W[/tex]), in joules, is equal to the change of its translational kinetic energy ([tex]\Delta K[/tex]), in joules:

[tex]W = \Delta K[/tex] (1)

By definitions of work and translational kinetic energy we expand the equation above:

[tex]F\cdot s = \frac{1}{2}\cdot m\cdot (v_{2}^{2}-v_{1}^{2})[/tex] (1b)

Where:

[tex]F[/tex] - External force applied on the sled, in newtons.

[tex]s[/tex] - Travelled distance, in meters.

[tex]v_{1}, v_{2}[/tex] - Initial and final velocities, in meters per second.

If we know that [tex]m = 11\,kg[/tex], [tex]v_{1} = 4\,\frac{m}{s}[/tex], [tex]v_{2} = 7\,\frac{m}{s}[/tex] and [tex]s = 3\,m[/tex], then the external force applied on the sled is:

[tex]F = \frac{m\cdot (v_{2}^{2}-v_{1}^{2})}{2\cdot s}[/tex]

[tex]F = \frac{(11\,kg)\cdot \left[\left(7\,\frac{m}{s} \right)^{2}-\left(4\,\frac{m}{s} \right)^{2}\right]}{2\cdot (3\,m)}[/tex]

[tex]F = 60.5\,N[/tex]

The magnitude of the force acting on the sled is 60.5 newtons.

Answer:

The energy will be increased by a factor 16

Explanation:

Mathematically, we have it that the energy carried by the sound wave is directly proportional to the square of the amplitude

So we have it that;

E = k * A^2

where E is the wave energy

K is the constant value

A is the amplitude value

So;

If E1 = k * (A1)^2

E2 = k * (A2)^2

But A2 = 4A1

E2 = k * (4A1)^2

E2 = k * 16(A1)^2

Divide E2 by E1

E2/E1 = k/k * 16(A1)^2/(A1)^2

E2/E1 = 16

E2 = 16 * E1

so simply, the energy will be increased by a factor of 16

Answer:

James Watson, Francis Crick, and Maurice Wilkins

Explanation:

The three scientists that used the available data ( x-ray images of DNA  provided by Rosalind Franklin) to correctly determine the structure of DNA are : James Watson, Francis Crick, and Maurice Wilkins.

These scientists discovered the structure of DNA in 1953  and they received, and they receive a Nobel Prize in Physiology or Medicine for their discovery

Answer:

Velocidad promedio = 5.29 m/s

Explanation:

Dados los siguientes datos;

Distancia = 900 m

Tiempo = 170 segundos

Para encontrar la velocidad media;

La velocidad se puede definir como la distancia recorrida por unidad de tiempo. La velocidad es una cantidad escalar y, como tal, tiene magnitud pero no dirección.

Matemáticamente, la velocidad viene dada por la fórmula;

[tex] Velocidad = \frac{distancia}{tiempo}[/tex]

Sustituyendo en la fórmula anterior;

[tex] Velocidad = \frac{900}{170}[/tex]

Velocidad = 5.29 m/s

Por lo tanto, la velocidad promedio del automóvil es 5.29 metros por segundo.

Answer:

Explanation

The most famous and common example is Christmas tree lights. You can't tell easily by looking at them whether they are in series or parallel. But you sure know the difference when one of them burns out. When that happens, the whole string goes dead. No matter what you do (other than find out which bulb burned out) will not fix the problem.

Another example is anything that is temperature controlled. For example a furnace is controlled by a thermostat. When the room temperature reaches a certain point, the thermostat is constructed in a certain way so that it forms an open circuit and no current can flow through it. The furnace motor turns off and the furnace stops pumping hot air into a room.

Answer:

Just as wavelength and frequency are related to light, they are also related to energy. The shorter the wavelengths and higher the frequency corresponds with greater energy. So the longer the wavelengths and lower the frequency results in lower energy. The energy equation is E = hν.

Explanation:

Explanation:

mass - 2kg

energy - 16 j

2

k.e- 1/2mv

2

16j=1/2×2×v

2

16×2/2=v

2

16=v

√16=v

V=4m/s

then momentum =mv

= 2×4

= 8 kgm/s

Answer:

(D)

Explanation:

When switch C is opened then, Current is not flowing across 3 So bulb 3 will go out.

But current is flowing across 1 and 2 bulb because their switch is closed

therefore bulb 1 and 2 will remain it.

Hence, option (D) will be correct.

Explanation:

The relation between the speed of sound and the temperature is direct. As the temperature increases, the speed of sound also increases. If the substance is heated up, its molecules moves faster. As a result they collide faster and hence the speed increases. There is a relation between the speed of sound and the temperature i.e.

[tex]v=331+0.61T[/tex]

Hence, this is the required solution.

Answer:

It will take 1 hr and 15 mins.

Explanation:

Let's look at the speed equation:

s=d/t

We want to find the time, and we have the speed and the distance, so we rearrange the equation. t will be on one side and s and d will be on the other side.

t=d/s

t=60km/(48km/h)

t=1.25h

Answer:

Por ela ter batido na trave, não tem como voltar 2x mais forte, por que toda ação correspondente a uma reação de igual intensidade, mas que atua no sentido oposto

Explanation:

Answer:

536 miles

Explanation:

If the airplane is running at a speed of 804 miles per hour, and covers a distance, x in a particular number of mile. The distance in mile can be gotten they the application of direct formula. Multiplying the speed by the time it took, and thus

804 mph * 40

Remember the time is in minutes and not hours, so, you convert it to hours.

804 * 40/60 hours =

536 miles

Answer:

h2 PRD algo trata gevbjjgcvnkoytewxc.

Answer:

12.5kg

Explanation:

The process is explained in the paper

Answer:

[tex] V = U + at[/tex]

Explanation:

Given the following data;

Initial velocity = 0 (since the stone is starting from rest).

Final velocity = 32 m/s

Acceleration = g = 10 m/s²

Time = 3.2 seconds

To show that the speed of the stone when it hits the ground is 32 m/s, we would use the first equation of motion;

[tex] V = U + at[/tex]

Where;

Substituting into the formula, we have;

[tex] 32 = 0 + 10*3.2[/tex]

[tex] 32 = 0 + 32 [/tex]

[tex] 32 = 32 [/tex]

Proven: 32 m/s = 32 m/s

Answer:

C, A and E

Explanation:

In theory you always assume that the prostive is going to the negtive and since C, A and E are in series they all will turn off will turn off

Answer:

Efficiency can be increase by using rollers in conjunction with the inclined plane. Wedge. The wedge is an adaptation of the inclined plane. It can be used to raise a heavy load over a short distance or to split a log.

Explanation:

Hope it helps

Answer:

0.00005 second =

50 microseconds

Time

0.00005

Second

50

Microsecond

Answer:

B. x - t graph

Explanation:

A position-time (x-t) graph is a graph of the position of an object against (versus) time.

Generally, the slope of the line of a position-time (x-t) graph is typically used to determine or calculate the velocity of an object.

An instantaneous velocity can be defined as the rate of change in position of an object in motion for a short-specified interval of time. Thus, an instantaneous velocity is a quantity that can be found by measuring the slope of a line that is tangent to a point on the graph.

Hence, the x - t graph also referred to as the position-time graph is used for determining the instantaneous velocity from the slope.

For example;

Given that the equation of motion is S(t) = 4t² + 2t + 10. Find the instantaneous velocity at t = 5 seconds.

Solution.

[tex] S(t) = 4t^{2} + 2t + 10[/tex]

Differentiating the equation, we have;

[tex] S(t) = 8t + 2 [/tex]

Substituting the value of "t" into the equation, we have;

[tex] S(5) = 8(5) + 2 [/tex]

[tex] S(5) = 40 + 2 [/tex]

S(5) = 42 m/s.

Answer:

B. x - t graph

Explanation:

Thus, an instantaneous velocity is a quantity that can be found by measuring the slope of a line that is tangent to a point on the graph. Hence, the x - t graph also referred to as the position-time graph is used for determining the instantaneous velocity from the slope.

Answer:

1530 m/s

Explanation:

Given that :

Speed = distance / time

Travel time take = 0.2 s

Distance covered = 306 metres

The speed of sound in the material :

Speed = distance / time = 306 m / 0.2

Speed = 1530 m/s

Answer:

I am not sure if this is the answer

acceleration: 2.2m/s

Explanation:

here

initial velocity(u): 11m/s

Final velocity(v): 33m/s

time taken(t): 10 s

now

a:v-u/t

or

acceleration:final velocity-initial velocity/time taken

or

a: 33-11/10

or

a:22/10, divide it

: a=2.2m/s#

Answer:

5ohms and 20ohms

Explanation:

Let the resistance of each wire be R1 and R2, if the equivalent resistance in series is 25 ohms, then;

R1 + R2 = 25 ...1

If the equivalent in parallel is 4 ohm, then;

1/R1 + 1/R2 = 1/4

R2+R1/R1R2 = 1/4

Cross multiply

4(R2+R1) = R1R2 ...2

From 1;

R1 = 25 - R2 ... 3

Substitute 3 into 2

4(R2+25-R2) = (25-R2)R2

4(25) = (25-R2)R2

100 = 25R2 - R2²

R₂² -25R₂+100 = 0

R₂² -20R₂-5R₂+100 = 0

R₂(R₂-20)-5(R₂-20) = 0

(R₂-5)(R₂-20)=0

R₂ = 5 or 20

Since R₁ = 25-R₂

R₁ = 25 - 5

R₁ = 20

Hence the resistances are 5ohms and 20ohms

Answer:

an o point i think

Explanation:

Answer:

1. A hiking

2. C

3. B

4. D

5. E

Answer:

Forces that the rider applies to the pedals, saddle and handlebars during speeding, hill climbing and starting are estimated from cine film records using elementary mechanics. The results are compared with force measurements obtained from an instrumented pedal. Pedal forces of up to three times bodyweight were recorded during starting. Handlebar loads were always significantly large.

Answer:

Water

Explanation:

Given the specific heat of oxygen is 918J/kg °C and the specific heat of water is 4181 J/kg °C.

Consider 1Kg mass of each substance.

Now 1 Kg of oxygen needs 918 J of energy to raise its temperature by 1 °C

Also, 1 Kg of water needs 4181 J of energy to raise its temperature by 1 °C.

Clearly water requires more energy when compared to oxygen.

Basically, specific heat capacity is the amount of energy required to raise the temperature of a 1 kg body by 1 °C.