5 Forces

Question 1

Scalar

Answer 1

Quantities which only have one magnitude (size).

E.g. volume, speed, mass, temperature

Question 2

Vector

Answer 2

Quantities which have magnitude and direction.

E.g. displacement, velocity, acceleration, force

Question 3

Displacement

Velocity

Answer 3

1) How far from a particular point.

2) How fast in a given direction.

Question 4

Speed is a ______. The equation is ?. The units are ___ or ___.

Answer 4

1) scalar
2) distance / time
3) m/s or ms⁻¹

Question 5

Forces are ______ quantities. It occurs when objects ________.

Answer 5

1) vector

2) interact

Question 6

Give five examples of contact forces.

Answer 6

• Friction
• Air resistance/drag (plane)
• Tension (pulling an elastic band)
• Normal contact force (desk exerting force up onto a book to support its weight)
• Upthrust

Question 7

Give three examples of non-contact forces.

Answer 7

• Gravitational force (satellite in orbit)
• Electrostatic force
• Magnetic force (magnets)

Question 8

If an object is in ___________ its _________ _____ equals zero. If an object is in ___________ it _______ __________.

Answer 8

1) equilibrium
2) resultant force
3) equailibrium
4) doesn’t accelerate

Question 9

Draw a free body diagram for a wheelbarrow being pushed by someone.

Answer 9

←•-→

→ = resultant force

Question 10

acceleration equation with units

Answer 10

a = v-u / t
m/s² = m/s ÷ s

Question 11

What do the following symbols mean?
• s 
• u 
• v 
• a 
• t

Answer 11

1) s = displacement (m)
2) u = inital/starting velocity/speed (m/s)
3) v = final velocity/speed (m/s)
4) a = acceleration (m/s²)
5) t = time (s)

Question 12

force equation with units (Newtons’s 2nd law)

Answer 12

F = ma
N = kg * m/s²

Question 13

An object traveling in a circle can have a constant speed, but its ________ __ _____ ________.
_______ is the tendency for objects to continue in the same state of ______.

Answer 13

1) velocity is still changing
2) Inertia
3) motion

Question 14

If an object falls in a _____, it eventually reaches a _______ ________ which we call its ________ ________.

Answer 14

1) fluid
2) maximum velocity
3) terminal velocity

Question 15

1) Centripetal force direction
2) What provides centripetal force?
3) What affects the centripetal force?

Answer 15

1) Force always points towards the centre of the circle
2) Friction provides the centripetal force
3) Velocity and the radius of the circle affect the size and the centripetal force acting on the car

Question 16

Name some factors which affect braking distance.

Answer 16

• Road conditions: adverse weather conditions e.g. wet/icy/snowy roads
• Vehicle conditions: worn brakes, worn tyres, over-inflated tyres, under-inflated tyres
• Weather conditions

Question 17

Newton’s 3rd Law

Answer 17

• 𝗙𝗼𝗿 𝗲𝘃𝗲𝗿𝘆 𝗮𝗰𝘁𝗶𝗼𝗻, 𝘁𝗵𝗲𝗿𝗲 𝗶𝘀 𝗮𝗻 𝗲𝗾𝘂𝗮𝗹 𝗮𝗻𝗱 𝗼𝗽𝗽𝗼𝘀𝗶𝘁𝗲 𝗿𝗲𝗮𝗰𝘁𝗶𝗼𝗻.
• When one object exerts a force on another, the other object exerts a force back
• The reaction force is of the same type and is equal in size but opposite in direction

Question 18

equation for stopping distance

Answer 18

stopping distance = thinking distance + braking distance

Question 19

Hooke’s law (equation)

Answer 19

force = spring constant * extension(compression)
F = ke
N = N/m * m

Question 20

What do the following symbols mean:
• k
• e

Answer 20

1) k = spring constant

2) e = extension

Question 21

equation for elastic potential energy

Answer 21

E = 0.5 * spring constant * (extension)² 
E(x) = 0.5 * k * e² 
J = 0.5 * N/m * m²

Question 22

1) Equation for momentum with units

2) Equation for total momentum

Answer 22

momentum = mass * velocity
kg m/s = kg * m/s

total momentum = 1st momentum + 2nd momentum

Question 23

equation for rate of change in momentum

Answer 23

F = m * Δv  /  Δt
N = kg*m/s / s

Question 24

equation of motion

Answer 24

v² = u² + 2as
m/s = m/s + (2 * m/s² * m)

Question 25

equation for kinetic energy

Answer 25

E(k) = 0.5 * m * v²
J = 0.5 * kg * m/s²

Question 26

equation for weight

Answer 26

weight = mass * gravitational field strength
W = mg
N = kg * N/kg

Question 27

equation for pressure in a column of liquid

Answer 27

P = height of column * density of liquid * gravitational field strength
P = hρg
Pa = m * kg/m³ * N/kg

Question 28

If a see-saw is balanced, what happens in terms of moments?

Answer 28

When balanced the clockwise moment is equal to the anticlockwise moment.
⚖️ ↻moment = ↺moment

Question 29

If one person sits on the left side of a balanced see-saw what happens in terms of moments?

Answer 29

The see-saw turns anticlockwise because now the clockwise moment is smaller than the anticlockwise moment.
↻moment < ↺moment

Question 30

What can you look at on a displacement-time graph to find where something is moving the slowest?

Answer 30

• You look at the gradient

* Lowest gradient is the slowest

Question 31

Why does pressure increase with depth?

Answer 31

• Greater depth, greater the weight above that point

* Greater the force on a surface at this point

Question 32

equation for pressure

Answer 32

P = force normal to a surface / area of that surface
P = F / A
Pa = N / m²

Question 33

Equation for moment of a force (turning effect)

Answer 33

M = force * distance
Nm = N * m
M = Fd

Question 34

Equation for work done

Answer 34

work done = force * distance (moved along line of action of force)
J = N * m
W = Fs