Work, energy and power

The application of a force that causes the body to move in the direction of the force is called

• Power

• Work

• Energy

• Efficiency

_______ is defined as the rate at which work is done.

• Efficiency

• Kinetic energy

• Potential energy

• Power

In which of the situations is NO work being done?

• pushing a box across the floor

• lifting a box from ground to a table top

• carrying a box up a flight of stairs

• holding a box

Principle of Conservation of Energy states that energy

• is created from motion

• energy cannot be transferred from one form to another.

• cannot be created or destroyed

• can only be converted into heat

Efficiency is a

• capacity to do work

• energy that it possesses due to its motion.

• energy held by an object because of its position relative to other objects

• comparison of the useful work or energy that a mechanical system produces to the work or energy that was put into the system.

A boy exerts an average force of 68N when he lifts a box 1.1m. How much work does he do?

• 74.8J

• 733.79J

• 61.82J

• 7.62J

25 N force is applied to a box and box moves 10m. Find the work done by the force.

• 250J

• 25.48J

• 25N

• 2452.5J

A boy pushes on a parked car with a force of 195N. The car does not move. How much work does the boy do?

• 19.88J

• 1912.95J

• 195J

• 0J

Ahmad lifts a 50 kg hiking bag onto his sholuders through a vertical distance of 1.65 m in 3s. Calculate the power produced by Ahmad.

• 809.33W

• 269.78W

• 27.5W

• 82.5W

Farah has a mass of 47 kg and is moving with initial speed of 5m/s. Find Farah's kinetic energy.

• 1175J

• 235J

• 587.5J

• 2305.35J