Gr 7 Exam

A boy is riding a skateboard. Why does the skateboard have the ability to do work?

• because it can slow down

• because the force applied by the rider acts in the same direction as the motion of the skateboard

• because it can change direction

• because the force applied by the rider acts in the opposite direction as the motion of the skateboard

Which of the following best defines energy?

• the resistance to motion

• how fast an object moves

• the ability to do work

• amount of force in a given time

A lightbulb uses 2,000 J of energy in 1 min and 20 s. What is the power of the lightbulb?

• 25 W

• 100 w

• 65 w

. Calculate the amount of work done when a grocery store stocker uses 120 N of force to lift a sack of flour 1.5 m onto a shelf.

• 180 J

• 200 j

• 150 j

Increasing the amount of work done can be accomplished by increasing what two things

Force - distance

• true

• false

The unit used to express power is called a watt

• true

• false

Which of the following is the energy of motion?

• Potential Energy

• Mechanical Energy

• Gravitational Energy

• Kinetic Energy

What term describes the energy that is stored due to the height of an object from the ground?

• Kinetic energy

• Chemical energy

• Gravitational Potential energy.

- A cow has mass 120 KG and is moving at 5 m/s along the farm. What is the kinetic energy of the cow?

• 1500J

• 1000 j

• 2000 j

A bird is 1 KG and is standing on o tree 10 m above the ground. What is the gravitational potential energy of the bird?

• 98J

• 100 j

• 76 j