Chapter 3: Forces and Pressure

Question 1

What is a force? Definition, SI unit, quantity)

Answer 1

A push or a pull that one object exerts on another object
Newton (N)
Vector

Question 2

What are the effects of forces?

Answer 2

1. Produce
2. Slow down
3. Speed up
4. Stop motion

Question 3

What ar the types of forces?

Answer 3

1. Contact forces

2. Non-contact forces

Question 4

Existence of contact forces and examples

Answer 4

Exist between objects that ar run contact

1. Normal reaction
2. Friction
3. Tension

Question 5

Existence of non-contact forces and examples

Answer 5

Do not require objects to be in contact to exist

1. Gravitational force
2. Magnetic force
3. Electric force

Question 6

Newton’s First Law and table

Answer 6

Newton’s First Law of Motion states that every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it

Balanced forces —> No resultant force —> No acceleration (1. At rest 2. Constant speed)

Question 7

Newton’s Second Law and table

Answer 7

Newton’s Second Law of Motion states that when a resultant force acts on an object of a constant mass, the object will accelerate in the direction of the resultant force
Unbalanced forces—>Resultant=/=0–>acceleration=/=(1. a>0 accelerate 2. a<0 decelerate

Question 8

Newton’s Third Law

Answer 8

Newton’s Third Law of Motion states that if body A exerts a force on body B, then body B will exert an equal and opposite force on body A

Question 9

What is friction?

Answer 9

The contact force that opposes or tends to oppose motion between surfaces in contact

Question 10

What are the positive effects of friction?

Answer 10

1: We can walk without slipping

2. Moving vehicles are able to slow down when needed

Question 11

What are the negative effects of friction?

Answer 11

1. Cars are less efficient by up to 20%

2. Moving parts of motors, engines and machines suffer wear and tear

Question 12

How to reduce negative effect of friction?

Answer 12

1. Wheels
2. Ball bearings
3. Lubricants and polished surfaces
4. Air cushion

Question 13

How to enhance positive effects of friction?

Answer 13

1. Treads
2. Parachute
3. Chalk

Question 14

What is pressure?(definition, SI unit, formula)

Answer 14

The force acting per unit area
SI unit: Pascal (Pa)
Formula: p = F/A
where,
p is pressure (Pa)
F is force (N)
A is area (m^2)