Physics Ch. 5 MC
A block of mass m=50kg moves on a rough horizontal surface with a coefficient of kinetic friction mu=0.5. The traveled distance is 20m. How much work is done by the friction force?
-5000J
A block of mass m is moved over a distance d. An applied force F is opposite to the block's displacement. How much work is done on the block by the force F?
-Fd
A 4kg block is attached to a vertical spring with a spring constant 800N/m. The spring stretches 5cm down. How much elastic potential energy is stored in the system?
1.0J
An applied force F accelerates an object from rest to a velocity v. How much work is done by the applied force F?
1/2mv2
A pole vaulter clears a bar that is 6.0m above the ground. With what velocity does the vaulter strike the mat in the landing area? (Disregard air resistance; g=9.8m/s2)
10.8m/s
A heavy block is suspended from a vertical spring. The elastic potential energy stored in the spring is 0.8J. What is the elongation of the spring if the spring constant is 100N/m.
13cm
A cashier pushed a grocery cart 5.0m with a horizontal force of 50.0N. How much work is done by the cashier on the grocery cart?
250J
A worker pushed a wheelbarrow with a horizontal force of 50.0 N over a level distance of 5.0m. If a frictional force of 43N acts on the wheelbarrow in a direction opposite to that of the worker, what net work is done on the wheelbarrow?
35J
A bullet penetrates a wooden block and loses its velocity by a half. What is the ratio between the initial kinetic energy of the bullet and the kinetic energy when the bullet leaves the block?
4/1
A container with a mass of 5kg is lifted to a height of 8m. How much work is done by the external force?
400J
A heavy block is suspended from a vertical spring. The elastic potential energy stored in the spring is 2J. What is the spring constant if the elongation of the spring is 10cm?
400N/m
A bobsled zips down an ice track starting at a vertical distance of 150m up the hill. Disregarding friction, what is the velocity of the bobsled at the bottom of the hill? (g=9.8)
54m/s
Which of the following energy forms is involved in winding a pocket watch?
Elastic potential energy
Which of the following energy forms is stores in any compressed or stretched object?
Elastic potential energy
A block of mass m is pulled over a distance d by an applied force F which is directed in parallel to the displacement. How much work is done on the block by force F?
Fd
A truck driver slams on the brakes of a moving truck with a constant velocity v as a result of his action the truck stops after traveling a distance d. If the driver had been traveling with twice the velocity, what would be the stopping distance compared to the distance in the first trial?
Four times greater
An object with a mass of 4kg is lifted vertically 3m from the ground level; another object II with a mass of 2kg is lifted 6m up. Which of the following statements is true?
III (Two objects have the same potential energy)
Which of the following energy forms is associated with an object due to its position?
Potential
Which of the following is the rate at which energy is transferred?
Power
In the following sentence, is the everyday or scientific meaning of work intended? A road cleaner does work shoveling snow.
Scientific
If the only force acting on an object during a given physical process is friction, which of the following assumptions must be made in regard to the object's kinetic energy?
The kinetic energy decreases
What happens to the kinetic energy of a moving object if the net work force done is positive?
The kinetic energy increases
As an object is lowered into a deep hole in the ground, which of the following assumptions must be made in regard to the object's potential energy?
The potential energy decreases
What happens to the gravitational potential energy of a moving object if the work done by the gravitational force is negative?
The potential energy increases
An object is thrown straight up. Which of the following is true about the sign of work done by the gravitational force while the object moves up and then down?
Work is negative on the way up, work is positive on the way down
A block of mass m is moved over a distance d. An applied force F is directed perpendicularly to the block's displacement. How much work is done on the block by the force F?
Zero
A truck driver is trying to push a loaded truck with an applied force. Unfortunately, his attempt was unsuccessful the truck stays stationary no matter how hard the driver pushes. How much work is done by the driver?
Zero
A construction worker holds a heavy tool box. How much work is done by the worker?
Zero.
A container with a mass of 5kg is lifted to a height of 8m and then returned back to the ground level. How much work is done by the gravitational force?
Zero.
The equation for determining gravitational energy is PEg=mgh. Which of the factor (s) in this equation is (are) NOT a property of an object?
both g and h
If the work done on an object results in a change in only the object's speed if the net work is negative
the object slows down and the net force does work on the object
