Mechanics - Forces

Question 1

What is a free body diagram?

Answer 1

a diagram which shows a single body on its own with forces acting on it - remember to add arrows as forces are vectors

Question 2

Do we label the centripetal force on a free body diagram?

Answer 2

no

Question 3

What is Newton’s 1st law?

Answer 3

‘object will remain at rest or move with constant velocity unless a resultant force acts on it’ - related to terminal velocity or being at rest

Question 4

Examples of some forces?

Answer 4

• tension
• drag
• friction
• reaction force
• weight
• push

Question 5

A body at which forces acting on it are balanced is said to be in?

Answer 5

equilibrium

Question 6

What direction does weight always act in?

Answer 6

towards the earth (downwards)

Question 7

What is Newton’s 2nd Law?

Answer 7

states that acceleration is proportional to the force ‘f= ma’ where mass is a constant

Question 8

What is Newton’s 3rd Law?

Answer 8

‘each force has an equal but opposite reaction force’ - these must be of the same type
or more simply
‘if body a exerts a force on body b then body b myst exert an equal but opposite force on body a’

Question 9

Conditions for newton’s third law?

Answer 9

• act on 2 separate bodies
• be of the same type
• act along the same line
• act in opposite directions
• be equal in magnitude

Question 10

Some examples of Newton’s Third Law?

Answer 10

• gravitational forces between earth moon
• electrostatic forces between charged objects
• people standing on something