Work and Energy + Light

In science, __________ is defined as the product of the force and the displacement of an object in the direction of the force.

• energy

• power

• work

• weight

The SI unit of work is ___________.

• Joule

• watt

• Newton

• Joule per second

A boy pushes a trolley with a horizontal force of 20 N. The trolley moves 5 m horizontally. What is the work done?

• 4 J

• 100 J

• 4 J/s

• 100 J/s

___________ is the rate at which work is done.

• power

• energy

• momentum

• torque

A simple machine is a device that helps us to do work easier.

• True

• False

________________ is the sum of the potential energy and kinetic energy.

• Elastic energy

• Gravitational energy

• Mechanical energy

• Chemical energy

Energy can change from one form into another, but it cannot be destroyed or created. This is known as the ______________________.

• law of conservation of mass

• law of consumption of energy

• law of gravitational force

• law of conservation of energy

Kinetic energy is the energy stored in a stationary object.

• True

• False

Potential energy is the energy stored in an object due to its position.

• True

• False

The food we eat contains energy that originally comes from _____________.

• plants

• farm animals

• the sun

• chemicals