The force of gravity produces acceleration in all C. freely falling objects and this is known as acceleration due to gravity
Explanation:
A body is said to be in free fall when there is only one force acting on the body: the force of gravity.
Gravity is a force that acts downward, i.e. towards the Earth's centre.
If we are near the Earth's surface, the magnitude of the force of gravity on a body is given by
where:
m is the mass of the body
g is known as the acceleration of gravity , whose value near the Earth's surface is 
).
We can apply Newton's second law on an object in free-fall, to find its acceleration. In fact, we have:
where F is the force acting on the body and a is its acceleration.
Solving for the acceleration,
And substituting F,
Therefore, every object in free-fall accelerates at towards the ground.
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The correct answer is A.
The coefficient of absorption of material A is 30%. So, the material will absorb 30% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 70% energy.
The coefficient of absorption of material B is 47%. So, the material will absorb 47% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 53% energy.
The coefficient of absorption of material C is 62%. So, the material will absorb 62% energy of the incident wave falling on it. Thus, the reflected wave will carry the rest 28% energy.
Hence, material C would be the best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
Answer:
0.78 m
Explanation:
By the conservation of energy, the energy that they gain from potential energy, must be equal to the kinetic energy. So, for Adolf:
Ep = Ek
ma*g*ha = ma*va²/2
Where ma is the mass of Adolf, g is the gravity acceleration (10 m/s²), ha is the height that he reached, and va is the velocity. So:
100*10*0.51 = 100*va²/2
50va² = 510
va² = 10.2
va = √10.2
va = 3.20 m/s
Before the push, both of them are in rest, so the momentum must be 0. The system is conservative, so the momentum after the push must be equal to the momentum before the push:
ma*va + me*ve = 0, where me and ve are the mass and velocity of Ed. So:
100*3.20 + 81ve = 0
81ve = 320
ve = 3.95 m/s
By the conservation of energy for Ed:
me*g*he = me*ve²/2
81*10*he = 81*(3.95)²/2
810he = 631.90
he = 0.78 m
Answer:
0.833 N
Explanation:
Formula for Kinetic Energy 
Formula for Potential Energy 
First we need to find the vertical distance between the maximum-angle position and the pendulum lowest point:
Using the swinging point as the reference, the vertical distance from the maximum-angle (34 degree) position to the swinging point is:
At the lowest position, pendulum is at string length to the swinging point, which is 1.2 m. Therefore, the vertical distance between the maximum-angle position and the pendulum lowest point would be
y = 1.2 - 1 = 0.2 m.
As the pendulum is traveling from the maximum-angle position to the lowest point position, its potential energy would be converted to the kinetic energy.
By law of energy conservation:
Substitute 
and y = 0.2 m:
At lowest point, pendulum would generate centripetal tension force on the string:
We can substitute mass m = 0.25, rotation radius L = 1.2 m and v = 2 m/s:
#4. It says "someone sitting in a chair" So the objects involved are the person and the chair. D is the answer because it talks about the action/reaction forces between the person and the chair.
#5. Work = Force (parallel to direction of distance) * distance. A, B and D are not correct because there is no distance. C. is the best answer
