Lift Problems

Lift Problems

This section is an application of Newton 2 and Newton 3.

Multiple Choice

The normal force is a reaction force upward on an object on its surface. This is an application of:

• Newton 1

• Newton 2

• Newton 3

Please note:

The normal force is equivalent to the force of tension in the cable attached to the lift, which is equivalent to the force of the scale exerted on the man.

T=N=Fscale

The force of the scale (Fscale) is the reading on the scale.

Draw

Consider a man in a lift standing on a scale. Draw the free body diagram of all the forces acting on the man.

Multiple Choice

If the lift is accelerating UPWARDS, which of the following is true:

• Fscale > Fg

• Fg > Fscale

Accelerating upwards

​For a lift accelerating upwards:

Multiple Choice

If the lift is accelerating DOWNWARDS, which of the following is true:

• Fscale > Fg

• Fg > Fscale

Accelerating downards

​For a lift accelerating downwards:

Multiple Select

Under which conditions will Fnet = 0N?

Select ALL answers that apply.

• When the object is accelerating
• When the object is at rest
• When the object is moving at constant velocity

• When the sum of all forces acting on an object is balanced

Stationary / Constant Velocity

​For a lift with no acceleration:

Multiple Choice

Consider a man in a lift with a mass of 80kg. What is the reading on the scale if he is travelling at constant velocity?

• 784N

• 184N

• -80N

• 847N

Multiple Choice

If the reading on the scale is 1000N, calculate the magnitude of the upwards acceleration.

• 2.4m/s²

• 2.7m/s²

• 3.2m/s²

• 3.7m/s²

Multiple Choice

If the lift is accelerating downwards at 5m/s², calculate the reading on the scale.

• 284N

• 184N

• 384N

• 584N

well done!

I'm proud of you for learning something new and exposing yourself to new knowledge and unfamiliar intellectual territory. Your books have been signed and you can collect them at the front.