physics

A 4 kg block is attached to a vertical spring with a spring constant 800 N/m. The spring stretches 5 cm down. How much elastic potential energy is stored in the system? A. 1.0 J B. 0.5 J C. 1.5 J D. 2.0 J E. 2.5 J

A. 1.0 J

An applied force F accelerates an object from rest to a velocity v. How much work is done by the applied force F? A. 1⁄2 mv2 B. mgh C. 1⁄2 kx2 D. mFd E. Zero

A. 1/2 mv2

The force as a function of displacement of a moving object is presented by the graph. How much work is done when the object moves from 0 m to 8 m? A. 40 J B. 20 J C. 0 J D. 10 J E. 5 J

A. 40 J

A heavy block is suspended from a vertical spring. The elastic potential energy is stored in the spring is 2 J. What is the spring constant if the elongation of the spring is 10 cm? A. 400 N/m B. 300 N/m C. 200 N/m D. 100 N/m E. 50 N/m

A. 400 N/m

What happens to the kinetic energy of a moving object if the net work done is positive? A. The kinetic energy increases B. The kinetic energy decreases C. The kinetic energy remains the same D. The kinetic energy is zero E. The kinetic energy becomes

A. The kinetic energy increases

A container with a mass of 5 kg is lifted to a height of 8 m. How much work is done by the external force? A. 400 J B. -400 J C. zero D. 50 J E. -50J

A.400 J

The force as a function of displacement of a moving object is presented by the graph. How much work is done when the object moves from 0 m to 5 m? A. 30 J B. 12.5 J C. 18 J D. 9 J E. 24 J

B. 12.5 J

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? A. Two times greater B. Four times greater C. The same D. Half as much E. One-quarter as much

B. Four times greater

A container with a mass of 5 kg is lifted to a height of 8 m. How much work is done by the gravitational force? A. 400 J B. -400 J C. zero D. 50 J E. -50J

B.-400 J

The elastic force as a function of displacement presented by the graph. How much elastic potential energy is stored in the spring when it is stretched by 10 cm? A. 0.1 J B. 0.2 J C. 0.3 J D. 0.4 J E. 0.5 J

C. .3 J

An object I with a mass of 4 kg is lifted vertically 3 m from the ground level; another object II with a mass of 2 kg is lifted 6 m up. Which of the following statements is true? I. Object I has greater potential energy since it is heavier II. Object II has greater potential energy since it is lifted to a higher position III. Two objects have the same potential energy A. I B. II C. III D. I and II E. II and III

C. III

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? A. Work is positive on the way up, work is positive on the way down B. Work is negative on the way up, work is negative on the way down C. Work is negative on the way up, work is positive on the way down D. Work is positive on the way up, work is negative on the way down E. Work is zero the way up, work is zero on the way down

C. Work is negative on the way up, work is positive on the way down

A container with a mass of 5 kg is lifted to a height of 8 m and then returned back to the ground level. How much work is done by the gravitational force? A. 400 J B. -400 J C. zero D. 50 J E. -50J

C.zero

A construction worker holds a heavy tool box. How much work is done by the worker? A. FGd B. - FGd C. mgh D. 1⁄2 mv2 E. zero

E. zero

A spacecraft moves around Earth in a circular orbit with a constant radius. How much work is done by the gravitational force on the spacecraft during one revolution? A. FGd B. - FGd C. mgh D. 1⁄2 mv2 E. zero

E. zero

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 the force F? A. mFd B. zero C. Fd D. F\d E. -Fd

c. Fd