COE concepts

An archer pulls back the bowstring to prepare to shoot an arrow as shown below.She uses an average force of 40 N, moving the bowstring 0.2 m. How much energy is stored in the bow?

• 8 J

• 24 J

• 16 J

• 36 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

At a weightlifting competition, two competitors lifted the same weight to the same height. The second competitor accomplished the lift 2 seconds faster than the first competitor. This demonstrated that the second competitor had more ____.

• energy than the first

• power than the first

• inertia than the first

• work than the first

A man ran on a treadmill for 1,800 seconds. At the end of his run, the treadmill indicated his energy output as 240,000 J. What average power did he generate?

• 666 W

• 66 W

• 133 W

• 7 W

Tags

NGSS.HS-PS3-1

Two students each carry a box up to the third floor of a building. The total mass of each student and the box she is carrying is the same. Roberta makes the trip in 45 s while Mary takes 30 s. Which of the following statements best describes this task?

• Roberta does more total work than Mary.

• Mary does more total work than Roberta.

• Roberta has a greater power output than Mary.

• Mary has a greater power output than Roberta.

The diagram shows a motor being used to lift a load with the use of a pulley.The motor is lifting the 6 kg box at a constant velocity. How much work is done on the box to lift it 2 m? (Assume no resistance from the pulley.)

• 3 J

• 4 J

• 60 J

• 120 J

Tags

NGSS.HS-PS3-1

The motor of one car is more powerful than the motor of another car. Which of the following must be true of the more powerful motor?

• It can do work more quickly.

• It can burn fuel more efficiently.

• It can operate for a longer time.

• It can store more potential energy.

Which of the following is the best example of work being done on an object?

• holding a 50 kg barbell

• keeping a board in place

• lifting a bag of groceries

• pushing on a car that will not move

An athlete is training for a race by performing timed trials of sprints up a staircase. Which set of variables most directly affects the athlete’s power?

• body weight, height climbed, width of steps

• body weight, time spent climbing, width of steps

• height climbed, time spent climbing, body weight

• height climbed, time spent climbing, width of steps

The figure below shows a wagon that moves from point X to point Y. Which of the following best describes the wagon’s change in energy as it coasts from point X to point Y?

• The wagon has the same kinetic energy at point Y and at point X.

• The wagon has more kinetic energy at point Y than at point X.

• The wagon has the same gravitational potential energy at point Y and at point X.

• The wagon has more gravitational potential energy at point Y than at point X.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

Which of the following describes the mechanical energy of a cart at rest at the top of a steep hill?

• The cart has no mechanical energy.

• The cart’s mechanical energy is all kinetic.

• The cart’s mechanical energy is all potential.

• The cart’s mechanical energy is half potential and half kinetic.

Tags

NGSS.MS-PS3-2