Question 1

An astronaut tosses a ball out in space where gravitational forces may be neglected. What will happen to the ball?

Accepted Answer

A)  It will stop as soon as the force the astronaut gave it is used up. 
B)  It will stop when the energy the astronaut gave it runs out. 
C)  It will stop after a short time because there is no gravity to keep it moving. 
D)  It will move in a circle like a boomerang. 
E)  It will be slowed down very gradually by collisions with molecules in space. 
A)  It will stop as soon as the force the astronaut gave it is used up. 
B)  It will stop when the energy the astronaut gave it runs out. 
C)  It will stop after a short time because there is no gravity to keep it moving. 
D)  It will move in a circle like a boomerang. 
E)  It will be slowed down very gradually by collisions with molecules in space.

Question 2

While running, a person dissipates about 0.6 J of mechanical energy per step per kilogram of body mass. If a 60-kg person runs with a power of 70 Watts during a race, how fast is the person running? Assume a running step is 1.5 m long.

Accepted Answer

The answer of While running, a person dissipates about 0.6...

Question 3

As a particle moves along the x axis it is acted upon by a single conservative force given by Fx = (20 − 4.0x) N where x is in m. The potential energy associated with this force has the value +30 J at the origin (x = 0). What is the value of the potential energy at x = 4.0 m?

Accepted Answer

A)  −48 J 
B)  +78 J 
C)  −18 J 
D)  +48 J 
E)  +80 J 
A)  −48 J 
B)  +78 J 
C)  −18 J 
D)  +48 J 
E)  +80 J

Question 4

A 1.0-kg block is released from rest at the top of a frictionless incline that makes an angle of 37° with the horizontal. An unknown distance down the incline from the point of release, there is a spring with k = 200 N/m. It is observed that the mass is brought momentarily to rest after compressing the spring 0.20 m. How far does the mass slide from the point of release until it is brought momentarily to rest?

Accepted Answer

A)  0.98 m 
B)  0.68 m 
C)  0.82 m 
D)  0.55 m 
E)  0.20 m 
A)  0.98 m 
B)  0.68 m 
C)  0.82 m 
D)  0.55 m 
E)  0.20 m

Exam 8: Conservation of Energy

An astronaut tosses a ball out in space where gravitational forces may be neglected. What will happen to the ball?

While running, a person dissipates about 0.6 J of mechanical energy per step per kilogram of body mass. If a 60-kg person runs with a power of 70 Watts during a race, how fast is the person running? Assume a running step is 1.5 m long.

As a particle moves along the x axis it is acted upon by a single conservative force given by Fx = (20 − 4.0x) N where x is in m. The potential energy associated with this force has the value +30 J at the origin (x = 0). What is the value of the potential energy at x = 4.0 m?

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As a particle moves along the x axis it is acted upon by a single conservative force given by F_x = (20 − 4.0x) N where x is in m. The potential energy associated with this force has the value +30 J at the origin (x = 0). What is the value of the potential energy at x = 4.0 m?