Work Physics

A crane lifts a steel beam weighing 8,000N, 300m in the air, then drops it onto a 20m high building below (for science!). The steel beam breaks through the ceiling. Assume that air resistance is negligible. Select the statement that best describes the scenario above.

• The beam has less energy when landing on the ground than it started with due to losing some to its surroundings

• The beam has the same amount of energy as it began with

• The kinetic energy as the beam touches the ground is equal to the potential energy it began with.

• The beam has a velocity of 19.8 m/s as it reaches the ground

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Rank the scenarios from least to greatest kinetic energy right before they hit the ground

• 2<3<1<4

• 2<1<3=4

• 2<1<3<4

• 1=2=3=4

Tags

NGSS.MS-PS3-1

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

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 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.MS-PS3-4

NGSS.MS-PS3-5

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

• True

• False

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

Ian and Steve ski down the 75 m slope in 80 seconds using 400 N of penguin force. Calculate their penguin power!

• 375 W

• 37.5 W

• 426.7 W

• 240 000W

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Mike and Peter are climbing to the top. Both take the same time, do the same route, but Mike has a mass of 25 kg while Peter has a mass of 30 kg. (He is a bit taller). Which penguin does the most work and why.

• Mike as shorter people have shorter legs and does more work.

• Peter as he does more work over the same time than Mike because he has a bigger weight force

• Mike and Peter do the same amount of work as they do the same route in the same time.

• Peter as he does the same amount of work but in a smaller amount of time.

Tags

NGSS.MS-PS2-2

A roller coaster goes over a 10m high hill at 20m/s. What kind of energy does the roller coaster have?

• Potential

• Kinetic

• Both

• Neither

Tags

NGSS.MS-PS3-2