Chapter 10 - Forces and Motion

Question 1

Newton’s First Law

Answer 1

✯ Newton’s first law states that every object will remain at rest or in uniform motion in a straight line unless acted upon by another force.

Question 2

Newton’s Second Law

Answer 2

F = M x A

F = Force (Newtons)

M = Mass (Kg)

A – Acceleration

Question 3

Newton’s Third Law

Answer 3

✯ Newton’s third law states that for every action force in nature, there is an equal and opposite reaction.

Question 4

What must the object’s force be equal to in equilibrium?

Answer 4

✯ If a particle is in equilibrium, then F = 0

Question 5

What is the formula for weight?

Answer 5

✯ The weight W is defined as W = mg

m – Mass

g – acceleration due to gravity.

g – 9.8

Question 6

Explain why an object moving at a constant speed in a circular path must have a resultant force acting on it.

Answer 6

✯ Velocity has direction whereas speed does not. If velocity changes therefore, there is a resultant force acting upon the object.

Question 7

What assumptions do we make for taught and slack strings?

Answer 7

✯ When the string is taut, initial velocity (u) and final velocity (v) are normal.

✯ However, when the string changes and becomes slack, the initial velocity (u) and final velocity (v) switch.

Question 8

What happens when the string goes from slack back to being taught again?

Answer 8

✯ When our string goes from slack back to being taut again it takes a further t seconds and thus our t for time is doubled.

Question 9

What do we assume occurs in the scenario that a particle in a pulley hits the ground?

Answer 9

✯ When a particle in a Pulley hits the ground, the other particle behaves like a particle moving freely under gravity, so acceleration is 9.8 ms^2.

Question 10

If a pulley is at rest, what is the force exerted at the pulley?

Answer 10

If at rest, F = 2T.