Answer:
total energy before transfer is equal to total energy after transfer
Answer:
1 is the correct one Answer
Two students race up a flight of steps together. "Student A" reaches the top of the steps 2 seconds ahead of
"Student B". Which of the students is more powerful?
A 3.00-g bullet has a muzzle velocity of 230 m/s when fired by a rifle with a weight of 25.0 N. (a) Determine the recoil speed of the rifle. 0.27 Correct: Your answer is correct. m/s (b) If a marksman with a weight of 650 N holds the rifle firmly against his shoulder, determine the recoil speed of the shooter and rifle. Incorrect: Your answer is incorrect.
Answer:
0.27 m/s and 0.01 m/s
Explanation:
Given that
Mass of the bullet, m = 3 g = 0.003 kg
Velocity of the bullet, v = 230 m/s
Weight of the rifle, w = 25 N
From this, we know that the mass of the rifle, M = 25/9.8 = 2.55 kg
Using the law of conservation of momentum, we know that
Momentum of the gun = momentum of the bullet
M.g * V.g = m.b * v.b
2.55 * V.g = 0.003 * 230
2.55V.g = 0.69
V.g = 0.69 / 2.55
V.g = 0.27 m/s
If weight of the shooter = 650, then his mass = 650/9.8 = 66.33 kg
The recoil speed of the shooter is
0.69 / 66.33 = 0.010 m/s
Suppose a race car accelerates horizontally 7.6 m/sec2 for 5.5 seconds. Assume the initial
velocity of the car is zero. How far did the race car travel while accelerating? This is a
displacement calculation.
Give your answer in standard form.
Answer:
d = 114.95 m
Explanation:
Givens:
a = 7.6 m/s^2
t = 5.5 s
v_i = 0 m/s
a = (v_f-v_i)/t
7.6 m/s^2 = (v_f-0 m/s)/5.5 s
v_f = (7.6 m/s^2)*(5.5 s)
v_f = 41.8 m/s
d = [(v_f+v_i)/2]*t
d = [(41.8 m/s)/2]*5.5 s
d = 114.95 m
The electric field strength at a point in space a fixed (known) distance from a point charge source is 5000 N/C. How does the field strength change if the source charge has doubled charge
Answer:
See explanation
Explanation:
Electric field strength;
E = kq/d^2
k= coulombs constant
q= magnitude of charge
d = distance if separation
If
d is constant
q = 2q
Then;
E = 2 kq/d^2
Hence, the electric field strength will double.
A force of 25 N acts on a 4.75 kg object for 8.4 s. What is the object's change in momentum?
what does it mean to say that mass is conserved during a physical change?
Answer:
Explanation:
When a physical change occurs, the mass of the substance is conserved. This means that the total mass of the substance remains the same from beginning to end. The physical properties of the substance, such as size and shape, may change, but the amount of matter in the substance does not change.
( sample response )
Calculate the average (mean) of these numbers: 6, 5, 7, 9.8*
1. 35
2. 8.75
3. 5
4. 7
Answer:
13.94 to 2 d.p
Explanation:
just add them all up and i am confused the ones you said or the ones listed ?
the one i did was the listed ones
If an ice cube has a mass of 5g and is left in the sun in a beaker, what will happen to its mass?
Answer:
The mass remains the same
Explanation:
An ice cube of mass 5g left in the sun in a beaker will have no mass difference.
For this system, mass is conserved.
The ice cube begins to melt and the state changes. The state change is from solid to liquid. Since no mass is loss, the mass of the liquid formed and the ice will remain the same. In retrospect, this physical change ensures that mass is conserved.Suppose you stand on a bathroom scale and it reads 580.0 N (about 130 lbs). Afterwards, a giant vacuuum machine sucks all the air out of the room. Would the scale reading increase, decrease, or remain the same
Answer:
the reading of the balance must decrease
Explanation:
The balance of the span is within a fluid the air, for which it is subjected to the pressure of the same, if we write the equilibrium equation we have
F_net = B -W - F_armosphere
in this case F_net = 540 N
where the thrust is given by Archimedes' principle which states that the thrust is equal to the weight of the fluid dislodged
B = ρ g V
in this case the density of the air is
ρ = 1.1 kg / m³
therefore the value of the thrust is small
the force of the air is
P = F / A
F = P A
the air pressure is approximately P = 1 10⁵ Pa
Thus
B <F_atmosphere
Now we can analyze what happens when we remove the air from the room, the pressure at atmospheric pressure decreases therefore the force of the air decreases, while there is some air the thrust is maintained even when it also decreases since the density of the air decreases when decreasing the Pressure.
Consequently, the reading of the balance changes depending on how the thrust and the air force decreases, in general the air force decreases much faster than the thrust, therefore the reading of the balance must decrease
An inductor is connected to a 120-V, 60-Hz supply. The current in the circuit is 2.4 A. What is the inductive reactance
Answer:
Inductive reactance is 50.00 ohms
Explanation:
Given the following data;
Voltage = 120v
Frequency = 60Hz
Current = 2.4 A
To find the inductive reactance;
Inductive reactance, XL = V/I
Where;
XL represents the inductive reactance. V represents the voltage. I represents the current.Substituting into the equation, we have;
XL = 120/2.4
XL = 50.00 ohms
A baseball player uses a pitching machine to help him improve his batting average. He places the 67.1 kg machine on a frozen pond. The machine fires a 0.101 kg baseball horizontally at a speed of 32.6 m/s. What is the magnitude of the recoil velocity of the machine
Answer:
The magnitude of the recoil velocity of the machine is 0.05 m/s.
Explanation:
Given;
mass of the baseball, m₁ = 0.101 kg
mass of the machine, m₂ = 67.1 kg
velocity of the baseball, v₁ = 32.6 m/s
let v₂ be the recoil velocity of the machine.
Apply the principle of conservation of linear momentum; the total momentum before and after firing the ball must be constant.
sum of the initial momentum of the ball and the machine = 0 (at rest)
sum of the final momentum of the ball and the machine = m₁v₁ + m₂v₂
Since total momentum is constant; m₁v₁ + m₂v₂ = 0
m₁v₁ + m₂v₂ = 0
(0.101 x 32.6) + (67.1)v₂ = 0
67.1v₂ = -3.2926
v₂ = (-3.2926) / 67.1
v₂ = -0.05 m/s (the negative sign shows that it is the opposite direction)
Thus, the magnitude of the recoil velocity of the machine is 0.05 m/s.
The % DV (percent Daily Value) is based on an average 2,000-calorie diet. One gram of carbohydrate provides 4 calories of energy. If Anna’s doctor recommends getting 60% of her calories from carbohydrates, how many grams of carbohydrates should she consume each day?
Answer:
300
Explanation:
If the %DV is based on an average 2,000 calorie diet, and one gram of carbohydrate provides 4 calories, you would divide 2,000 by 4.
2,000 divided by 4 equals 500.
If Anna's doctor recommends 60% of her calories, you find out how much 60% of 500 is.
60% of 500 is 300.
Anna should consume 300 grams of carbohydrates daily.
Hope this helps!
Answer:
300
Explanation:
The force f is given in terms of time t and displacement X by the equation F= Asin Bx +C sin dt. What is the dimension of D/B?
Answer:
Here's what I think,
A_Trigonometric_ratio (whatever)
The general form of sin/cos/tan(angle).
So here as in the general form the "whatever" is always an "angle" input which (may sound a bit unfair but) is a dimensionless quantity.
As mentioned in your question,
F= Asin(Bt) + C cos (Dy)
Dimentions of these terms will be same (by homogenity of dimensions).
So what we gotta do here is make Bt and Dy dimensionless for this whole equation to work.
According to your question t is time,
So to make Bt dimensionless,
B must be equal to inverse of time i.e T^(-1)
Using the same process on Dy, gives inverse of length i.e L^(-1)
So,
B= M^(0)L^(0)T^(-1)
D = M^(0)L^(-1)T^(0)
The dimension of D/B then will be M^(0)L^(-1)T^(1)
A plastic ball has mass M. It floats in water with (1/5)th of its volume under the water line. What downward force must be applied to the ball to submerge it and hold it at rest below the surface of the water
Answer:
F = -4/5 W
Explanation:
We will do this exercise in parts, let's start with the data, The ball must be in balance
B -W = 0
B = mg (1)
where the thrust is given by Archimedes' principle
B = ρ g V_liquid
In the problem we are told that the volume of the submerged body is 1/5 of the volume of the body, let's use the subscript 2 for the ball and the subscript 1 for the liquid
V₁ = [tex]\frac{1}{5}[/tex] V₂
if we use the concept of density for the body
ρ₂ = m / V₂
m = ρ₂ V₂
We can see that mass and volume are directly proportional, so we can use a rule of three to find the submerged mass. If mass M is in volume V₂ what mass is there in volume V₂ /5
m₂ = [tex]\frac{V_{2} }{5} \frac{M}{V_{2} }[/tex]
m₂ = M / 5
we substitute in equation 1
B = M / 5 g
This is the thrust that is an upward vertical force, therefore to submerge the whole ball we must apply a downward vertical force equal to the rest of the weight, the equilibrium condition in this case is
B -W - F = 0
F = B -W
F = [tex]\frac{M}{5}[/tex] g - M g
F = -4/5 Mg
F = -4/5 W
The negative sign indicates that the force is vertical down
A system dissipates 12 JJ of heat into the surroundings; meanwhile, 28 JJ of work is done on the system. What is the change of the internal energy ΔEthΔEthDeltaE_th of the system?
Given that,
A system dissipates 12 J of heat into the surroundings.
28 J of work is done on the system.
To find,
The internal energy of the system.
Solution,
The first law of thermodynamics is used here. According to this law,
[tex]\Delta E=Q-W[/tex]
Q is heat and W is work done
Here,
Q = -12 J is the heat dissipated by the system
W = -28 J is the work done on the system
ATQ,
[tex]\Delta E=(-12)-(-28)\\\\=-12+28\\\\=16\ J[/tex]
So, the change of internal energy of the system is 16 J.
What is the internal resistance of a 12.0 V car battery whose terminal voltage drops to 8.2 V when the starter draws 75 A
Answer:
The internal resistance of the cell is 0.051 ohm.
Explanation:
Given;
emf of the battery, E = 12 V
terminal voltage of the cell, V = 8.2 V
current in the circuit, I = 75 A
let the potential drop of the cell due to internal resistance (r) = Ir
The internal resistance of the cell is calculated from the equation below;
E = V + Ir
where;
r is the internal resistance of the cell
[tex]Ir = E - V\\\\r = \frac{E-V}{I} \\\\r = \frac{12-8.2}{75} \\\\r = 0.051 \ ohm[/tex]
Therefore, the internal resistance of the cell is 0.051 ohm.
explain why astronauts around the earth either in spaceship, a space station, or on a spacewalk appear to be weightless but are not actually weightless.
Answer:
Zero gravity
Explanation:
Astronauts around the earth either in spaceship, a space station or on a space walk appear to be weightless because of the zero gravity in such environment.
Weight is a function of the mass and acceleration due to gravity a body has.
Weight = mass x acceleration due to gravity
In a place where acceleration due to gravity is 0, the weight would be zero and a person would appear to be weightless.
A ball is thrown straight up and rises to a maximum height of 22 m. At what height is the speed of the ball equal to half of its initial value
Answer:
The height of the ball when the speed of the ball is half of its initial value is 16.5 m
Explanation:
Given;
maximum height reached by the ball, h = 22 m
let the initial velocity of the = u
The equation of maximum height reached by the ball is calculated as;
v = u² - 2gh
where;
v is the final velocity at the maximum height = 0
0 = u² - (2 x 9.8)22
0 = u² - 431.2
u² = 431.2
u = √431.2
u = 20.765 m/s
Half of the initial speed = ¹/₂ x 20.765 m/s = 10.383 m/s
The height of the ball at this half value of speed is calculated as;
v² = u² - 2gh
where;
v is the final speed = 10.383 m/s
u is the initial speed = 20.765 m/s
(10.383)² = (20.765)² - (2 x 9.8)h
(2 x 9.8)h = (20.765)² - (10.383)²
19.6h = 323.379
h = 323.379 / 19.6
h = 16.5 m
Therefore, the height of the ball when the speed of the ball is half of its initial value is 16.5 m
A pilot must fly his plane due north to reach his destination. The plane can fly at 300 km/h in still air. A wind is blowing out of the northeast at 90 km/h. (a) What is the speed of the plane relative to the ground
Answer:
229.5 km/h
Explanation:
Given that
Velocity of the plane relative to the ground = V.pg = ?
Velocity of air relative to the ground = V.ag = 90 km/h
Velocity of the plane relative to air = V.pa = 300 km/h
V.pg = V.ag + V.pa
Where
V.ag = 90 km/h
= -90 cos 45i - 90 sin 45j
V.pa = 300 km/h
= 300 cos θi + 300 sin θj
V.pg = [-90 cos 45i - 90 sin 45j] + [300 cos θi + 300 sin θj], on rearranging and collecting like terms
V.pg = [300 cos θ - 90 cos 45]i + [300 sin θ - 90 sin 45]j
If vector i = 0, then
300 cos θ - 90 cos 45 = 0
300 cos θ = 90 cos 45
cos θ = 90 cos 45 / 300
cos θ = 63.6396 / 300
cos θ = 0.2121
θ = cos^-1 0.2121
θ = 77.75
We then use this θ to find vector j
V.pg = 300 sin θ - 90 sin 45
V.pg = 300 sin77.75 - 90 sin45
V.pg = 293.1693 - 63.6396
V.pg = 229.5297 km/h
A tourist drops (from rest) a ping pong ball from the top of the tower, which has a height of 324 meters. Assuming no air resistance, how long does it
Answer:
8.13secs
Explanation:
From the question weal are given
Height H =324m
Required
time it takes to drop t
Using the equation of motion
H = ut + 1/2gt²
Substitute the given values
324 = 0(t)+1/2(9.8)t²
324 = 1/2(9.8)t²
324 = 4.9t²
t² =324/4.9
t² = 66.12
t = √66.12
t = 8.13secs
Hence the time taken to drop is 8.13secs
The velocity of a bob on a simple pendulum at the lowest position is 10.56 m/s. What is the maximum vertical height it is able to rise to?
um I do not know sorry
Explanation:
ummmmmmjjhfgfffff
A bungee cord stretches 25 meters and has a spring constant of 140 N/m. How much energy is stored in the bungee cord
Answer:
The energy stored in the bungee cord is 43,750 J.
Explanation:
Given;
extension of the bungee cord, x = 25 m
spring constant of the bungee cord, k = 140 N/m
The elastic potential energy stored in the bungee cord is calculated as;
U = ¹/₂kx²
U = ¹/₂(140)(25)²
U = 43,750 J
Therefore, the energy stored in the bungee cord is 43,750 J.
How come the arrow points the other direction when we look at it through a glass of water?
What are input energy and output energy?
Answer:
Explanation:
Input refers to the amount of energy put into a device, and output refers to the amount of energy that comes out. A device may change the type of energy but not the amount. For example, a light bulb's input energy is the form of electrical energy, and its output energy is in the form of light and heat. Efficiency.
for the same type of atom with 8 protons, 9 neutrons, and 10 electrons, what type of atom or ion is it
Answer:
O²⁻
Explanation:
Number of protons = 8
Number of neutrons = 9
Number of electrons = 10
What type of atom or ion is it = ?
Solution:
Protons are the positively charged particle in an atom
Neutrons do not carry any charges
Electrons are negatively charged particles
For this atom, the number of protons helps to identify what specie it is; so this is an oxygen atom.
Now,
Charge = Number of protons - Number of electrons
Charge = 8 - 10 = -2
The charge on the atom is -2 and so it is an oxygen ion with -2 charge
The ion is O²⁻
A truck is carrying a load of furniture and has a momentum of 33,842 kg m/s. If half of the furniture falls off the truck (mass is cut in half), what is the truck’s new momentum?
Answer:
16921
Explanation:
Usually, if and when the truck does lose part of its load, or load gets cut into half, then it's momentum gets reduced to half of the original momentum. This is because, from the definition of momentum, we understand that it's the multiplication of mass and velocity. This means that if the mass gets reduced to half, then the total momentum goes ahead to be reduced to half just as well.
New momentum = 1/2 * 33842
New momentum = 16,921 kg∙m/s.
A truck engine slows down from 3700 rpm to 1800 rpm in 4.25 s. How many revolutions were made by the engine during this time
Answer:
194.81 revolutions
Explanation:
Given that,
Initial angular velocity, [tex]\omega_i=3700\ rpm[/tex]
Final angular velocity, [tex]\omega_f=1800\ rpm[/tex]
Time, t = 4.25 seconds
We need to find the number of revolutions occur during this time.
3700 rpm = 387.46 rad/s
1800 rpm = 188.49 rad/s
Let [tex]\alpha[/tex] is angular acceleration. Using first equation to find it.
[tex]\alpha =\dfrac{\omega_f-\omega_i}{t}\\\\\alpha =\dfrac{188.49 -387.463 }{4.25}\\\\\alpha =-46.81\ rad/s^2[/tex]
Now let us suppose that the number of revolutions are [tex]\theta[/tex].
[tex]\theta=\dfrac{\omega_f^2+\omega_i^2}{2\alpha}\\\\=\dfrac{188.49 ^2-387.463 ^2}{2\times -46.81}\\\\=1224.087\ rad[/tex]
or
[tex]\theta=\dfrac{1224.087}{2\pi}\\\\=194.81\ rev[/tex]
Hence, there are 194.81 revolutions.
Which color of visible light has a higher frequency than blue light?
A. Green
B. Yellow
C. Red
D. Violet
Answer:
D. violet
Explanation:
think of a UV light
Find the length of a simple pendulum that has a period of 1.00 s. Assume that the acceleration of gravity is g
Answer:
The length of the simple pendulum is 0.248 m.
Explanation:
Given;
period of the simple pendulum, T = 1.00 s
let the length of the simple pendulum = L
The period of oscillation of a simple pendulum is calculated as;
[tex]T = 2\pi \sqrt{\frac{l}{g} } \\\\\frac{T}{2\pi } = \sqrt{\frac{l}{g} }\\\\\frac{T^2}{4\pi ^2 } = \frac{l}{g}\\\\l = \frac{gT^2}{4\pi ^2 } \\\\l = \frac{(9.8)(1)^2}{4\pi ^2 } \\\\l = 0.248 \ m[/tex]
Therefore, the length of the simple pendulum is 0.248 m.
if you go to space at 15000 mph. how long would it take you at the same speed to reach mars
Answer:
if your going 15000 mph all you can do is accelerate or go fast unless there is a opposite
Explanation: