S3 Physics g10

In which of the following sentences is work used in the scientific sense of the word?

• Holding a heavy box requires a lot of work.
  

• A scientist works on an experiment in the laboratory.
  

• Sam and Rachel pushed hard, but they could do no work on the car.

• John learned that shoveling snow is hard work.

In which of the following sentences is work used in the everyday sense of the word?

• Lifting a heavy bucket involves doing work on the bucket.
  

• The force of friction usually does negative work.
  

• Sam and Rachel worked hard pushing the car.

• Work is a physical quantity.

A force does work on an object if a component of the force

• is perpendicular to the displacement of the object.
  

• is parallel to the displacement of the object.
  

• perpendicular to the displacement of the object moves the object along a path that returns

  the object to its starting position.
  

• parallel to the displacement of the object moves the object along a path that returns the

  object to its starting position.

Work is done when

• 1. the displacement is not zero.

• 1. the displacement is zero.

• 1. the force is zero.

• 1. the force and displacement are perpendicular.

What is the common formula for work? Assume that W is the work, F is a constant force, v is the change in velocity, and d is the displacement.

• W=Fv

• W=Fd

• W=Fd²

• W=F²d

If the sign of work is negative,

• the displacement is perpendicular to the force.
  

• the displacement is in the direction opposite the force.

• the displacement is in the same direction as the force.

• no work is done.

In which of the following scenarios is work done?

• A weightlifter holds a barbell overhead for 2.5 s.
  

• A construction worker carries a heavy beam while walking at constant speed along a flat

  surface.
  

• A car decelerates while traveling on a flat stretch of road.

• A student holds a spring in a compressed position.

In which of the following scenarios is no net work done?

• A car accelerates down a hill.
  

• A car travels at constant speed on a flat road.
  

• A car decelerates on a flat road.

• A car decelerates as it travels up a hill.

A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone?

• 0J
  

• 0.5J

• 2J
  

• 20J

A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket?

• –25J
  

• 0J

• 25J
  

• 50J