Forces ⚖️

Question 1

Define Newton’s First Law and name an example.

Answer 1

• An object will remain stationary or continue to move at a constant speed as long as the forces acting on it are balanced.
• E.g. The simple pendulum!

Question 2

Why is demonstrating Newton’s First Law in the lab difficult and how could you overcome this challenge?

Answer 2

• Because friction will always slow down an object.
• Use an air track (like you see in air hockey) or a hover craft to reduce the friction.

Question 3

Define Newton’s Second Law and state the formula linking force, mass, and acceleration.

Answer 3

• If there is a resultant force acting on an object then it will start to change speed (accelerate/decelerate)
• Formula: F = ma
  (Force = mass x acceleration).

Question 4

Define Newton’s Third Law.

Answer 4

For every action there is an equal and opposite reaction.

Question 5

What are directly proportional?

Answer 5

Force and extension.

Question 6

State Hooke’s Law Equation and the equation for working out the extension of an object.

Answer 6

• Force (N) = Spring Constant (N/m) x Extension (m)
  F = kx or F = ke
  This equation only works if the elastic limit isn’t exceeded.
• Extension = new length - original length.

Question 7

What is a moment?

Answer 7

• A moment is the turning effect of a force around a pivot.

Question 8

What is the formula for moments?

Answer 8

Moment (Nm) = Force (N) x Perpendicular Distance to the pivot (m)

Question 9

What is needed for an object to be in equilibrium?

Answer 9

The anti-clockwise moment must equal the clockwise moment.