Physics Power

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

• holding a heavy stack of books while standing
• carrying a heavy stack of books
• dropping a stack of books onto a table
• picking up a pile of books from the floor

Tags

NGSS.MS-PS2-4

NGSS.MS-PS3-5

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

What is the difference between calculating power and work?

• Power takes into account the time it takes to complete a task
• Work takes into account the time it takes to complete a task
• Power is force/area
• Work is force/area

Tags

NGSS.HS-PS2-1

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.MS-PS2-2

NGSS.MS-PS3-5

How much work is done carrying a 10-N box horizontally across a floor for 8 m?

• 80 J
• 10 J
• 8 J
• 0 J

You do work against gravity when you walk up some stairs.

• True

• False

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 m*g*h, and work is 1/2*m*v²

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

• Weight

• Pulling force

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