P5 - Forces

Question 1

What are forces?

What are the examples of the 2 types of forces?

Answer 1

Force = a push or pull in a particular direction.

Forces are vector quantities.

Contact forces:
• friction, upthrust, air resistance, push/pull

Non contact forces:
• weight, electrostatic, magnetic

Question 2

What are vectors and scalars?

Answer 2

Scalar = a quantity that has size (magnitude) but no direction

• time, distance, speed, energy, mass, temperature

Vector = a quantity that has a size (magnitude) and direction

• force, displacement, velocity, acceleration, weight, momentum

Question 3

What is Newton’s first law?

Question 4

What is Newton’s second law?

Answer 4

F = m a

Resultant force = mass x acceleration

Question 5

What is Newton’s third law?

Answer 5

Whenever two objects interact, the forces they exert on each other are equal and opposite.

Question 6

What is inertia?

Answer 6

The tendency for motion to remain unchanged.

Question 7

What is gravitational force?

What are it’s 2 effects?

Answer 7

Gravitational force = the force of attraction between masses.

• Gravity attracts all masses but it is only noticeable when the mass is really big.

Gravitational force has 2 effects:
• makes everything fall towards ground
• gives everything a weight

Question 8

What is the difference between mass and weight?

Answer 8

Mass = the amount of stuff in an object
• Is the same value anywhere in the universe
• Measured in Kg - using balance, scales

Weight = the force acting on an object due to gravity
• Is different in different locations
• Measured in N - using newton meter

Question 9

What is the equation of weight?

Answer 9

Weight = mass x gravitational field strength

(N) = (kg) x (N/kg)

Question 10

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