AP Physics Work and Energy

In which of the following situations do your arms do work on books?

• holding a heavy stack of books while standing

• pushing down on a heavy stack of books lying on a table

• dropping a stack of books onto a table

• picking up a pile of books from the floor

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J
• 45 J
• 0 J
• 5 J

What unit do we use for measuring power?

• Watts 
• Joules 
• Newtons 
• ft/lbs

Mr. B's and Mr. P's classes competed in a game of tug of war. Mr. B's class pulled to the right with a force of 4,000 N. Mr. P's class pulled to the left with a force of 5,000 N. As a result the rope moved 5.1 m to the left. How much work was done by the net force?

• 4100 J

• 3100 J

• 5100 J

• 45900 J

Tags

NGSS.HS-PS2-1

Which are correct units for work?

• N x s

• N x m

• J/s

• W

Which are correct equivalent units for power?

• N x s

• N x m

• J

• J/s

How are work and energy related?

• The work done by an external force acting on an object causes a change in the mechanical energy of the object.

• Work is the same thing as energy. They are equal.

• Energy is mgh, and work is mv²/2

Tags

NGSS.HS-PS2-1

Which principle states that whenever work is done, energy changes form?

• Law of Conservation of Energy

• Work-Energy Theorem

• Newton's Fourth Law

• Efficiency

If you pull the trolley along a flat floor horizontally. Which force do you use to calculate the work done.

• Weight

• Pulling force

• Normal forrce

• Friction

Tags

NGSS.HS-PS2-1

Mike and Ian move 50 m on a snow lift which uses 750 N of force to move them in 75 seconds. Calculate the power of the lift.

• 750 W

• 500 W

• 7500 W

• 2812500 W