Introduction to Forces and Free Body Diagrams

Look at the following steps for drawing a free-body diagram, and determine what Step 4 should be:

• Draw in an arrow for the net force

• Calculate the acceleration using the mass of the object

• Draw all of the objects that are pushing / pulling at the ends of the arrows

• Make sure the length of each arrow correctly represents the strength of the force

A student is analyzing the forces on a 400 kg car driving at a constant velocity of 20 m/s. What is wrong with the student's force diagram?

• The forward force should be 20 N rather than 8000 N since F_net = m·a

• The diagram shows a net force but the net force on the car should be zero

• There cannot be any forces on the car if it has a constant velocity so there should be no arrows

• There should be more backward force on the car because the care is slowing down

Tags

NGSS.MS-PS2-2

The force that keeps objects on top of surfaces instead of letting them sink into the surface is known as:

• normal

• abnormal

• static

• inertia

A person stands on a scale in an elevator. If the elevator accelerates upward, what happens to what the scale reads (i.e. the normal force)?

• It increases.

• It stays the same.

• It decreases.

• It changes to a negative value.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A man standing on a scale in an elevator notices that the scale reads 40 newtons greater than his normal weight. Which type of movement of the elevator could cause this greater-than-normal reading?

• moving downwards and slowing down

• moving upwards and slowing down

• moving upward at a constant speed

• moving downward and speeding up

Tags

NGSS.MS-PS2-2

What does the F stand for on a free-body diagram?

• Free

• Fan

• Net

• Force

Tags

NGSS.HS-PS2-1

What is the NET FORCE of this diagram?

• 17 N, right

• 17 N, left

• 23 N, right

• 12 N, up

Tags

NGSS.MS-PS2-2

Which of the following is true about this free-body diagram?

• the forces are are balanced

• the object is free-falling

• the object is moving upward

• the forces are unbalanced

Tags

NGSS.MS-PS2-2

The name for this type of diagram is...

• free body diagram

• box diagram

• free box diagram

• stem and leaf diagram

Tags

NGSS.MS-PS2-2

Name the missing force...

• frictional force

• weight force

• thrust

• buoyant force

Tags

NGSS.MS-PS2-2