Energy Midterm

The SI unit of work is?

• Joules
• Watts
• Newtons
• meters

Tags

NGSS.HS-PS2-1

The SI unit for power is...?

• Watts
• Joules
• Newtons
• Meters

A crane lifts an 8-m long steel girder weighing 2600 N up 15 m off the ground. The crane did ___ of work.

• 0 J

• 39000 J

• 20800 J

• 2600 J

A crane carries an 8-m long steel girder weighing 2600 N out 12 m to the end of the crane. The crane did ___ of work.

• 0 J

• 2600 J

• 20800 J

• 31200 J

A 40-kg person is climbing 3 m up a flight of stairs in 6 seconds. How much power did they exert climbing the stairs?

• 400 W

• 1200 W

• 200 W

• 120 W

A force changes over time. During which section does that force do the largest magnitude of work?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

A force changes over time. During which section is the system in static equilibrium?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

A force changes over time. During which section is the system in dynamic equilibrium?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-2

A force F at an angle θ above the horizontal is used to pull a heavy suitcase of weight mg a distance d along a level floor at constant velocity. The coefficient of friction between the floor and the suitcase is µ. The work done by the frictional force is:

• – µFdcosθ

• –Fdcosθ

• –µmgd

• –µmgdcosθ

Tags

NGSS.HS-PS3-1

A pendulum bob of mass m on a cord of length L is pulled sideways until the cord makes an angle θ with the vertical as shown in the figure to the right. The change in potential energy of the bob during the displacement is:

• mgL(1–cos θ)

• mgL(1–sin θ)

• mgLsinθ

• mgLcosθ