Energy MCQ

A container with a mass of 5kg is lifted to a height of 8m. How much work is done by the gravitational force?

-400 J

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 800 N/m. The spring stretches 5 cm down. How much elastic potential energy is stored in the system?

1.0 J

A heavy block is suspended from a vertical spring. The elastic potential energy is stored in the spring is 0.8 J. What is the elongation of the spring if the spring constant is 100 N/m

13 cm

A motorbike engine can develop a power of 90000 W in order to keep a constant velocity of 30 m/s. What is the pushing force?

3000 N

A container with a mass of 5kg is lifted to a height of 8m. How much work is done by the external force?

400 J

A heavy block is suspended from a vertical spring. The elastic potential energy is stored in the spring is 2J. What is the spring constant if the elongation of the spring is 10cm?

400 N/m

A machine does 2500 J of work in 1 minute. What is the power developed by the machine?

42 W

A car travels with a constant speed of 15 m/s. The car's engine produces a 4000 N pushing force in order to keep the speed constant. How much power is developed by the engine?

60000 W

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?

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

What happens to the total energy of a moving object if all the applied forces are conserved?

It remains constant

What happens to the kinetic energy of a moving object if the net work done is positive?

The kinetic energy increases

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 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

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?

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