Topic 2

Question 1

Equation: SUVAT *

Answer 1

v = u + at

s = ut + ½at²

v² = u² +2as

s = (u+v)t / 2

Question 2

What is a scalar quantity?

Answer 2

One that only measures magnitude.

Question 3

What is a vector quantity?

Answer 3

One that measures both magnitude and direction.

Question 4

How do you find a resultant force using vectors?

Answer 4

Use trigonometry or a scale drawing.

Question 5

What is an assumption you make when using SUVAT equations?

Answer 5

That acceleration is constant.

Question 6

How do you solve projectile questions?

Answer 6

Treat horizontal and vertical motion separately.

Question 7

How does air resistance affect the flight of a projectile?

Answer 7

It is a force which acts against the motion of a projectile, which reduces its speed meaning it doesn’t travel as far.

Question 8

What does Newton’s 1st Law of Motion state?

Answer 8

A body will remain at a state of constant velocity unless acted upon by an external resultant force.

Question 9

What does Newton’s 2nd Law of Motion state?

Answer 9

The acceleration is directly proportional to and in the same direction as the resultant force acting upon it.

Question 10

Equation: Newton’s 2nd Law of Motion *

Answer 10

∑F = ma

∑F = resultant force acting on a body (N)

m = mass of body (kg)

a = acceleration of body (ms⁻²)

Question 11

What an assumption made when using the equation for Newton’s 2nd Law of Motion?

Answer 11

Mass must be constant.

Question 12

What is terminal velocity?

Answer 12

The faster you travel, the more air you displace, increasing the opposing force of air resistance which acts against you. When this force has the same magnitude as your thrust/weight, your resultant force becomes zero, and so you travel at a constant velocity.

Question 13

What does Newton’s 3rd Law state?

Answer 13

For every action there is an equal and opposite reaction.

Question 14

What are Newton’s 3rd Law pairs?

Answer 14

1) Act on different bodies. 2) The sane type of force. 3) Equal magnitude. 4) Act in opposite directions. 5) Act among the same line.

Question 15

Equation: Momentum *

Answer 15

p = mv

p = momentum (kgms⁻¹)

m = mass (kg)

v = velocity (ms⁻¹)

Question 16

Definition: Principle of conservation of momentum

Answer 16

Providing no external forces act on the system, the sum of the initial momentum is equal to the sum of the final momentum.

Question 17

What is the relationship between the forces exerted on each object during a collision?

Answer 17

No matter the mass of each object, the force each object exerts on the other is of equal magnitude but opposite direction.

Question 18

Definition: Principle of moments

Answer 18

For a body to be in rotational equilibrium, the sum of the clockwise moments must equal the sum of the anti-clockwise moments, provided that the moments are taken about the same point.

Question 19

Equation: Moments *

Answer 19

Moment = Fx

F = force (N)

x = perpendicular distance from pivot to line of action of force (m)

Question 20

Definition: Centre of gravity

Answer 20

The point through which all of the weight of the body appears to act, and the body is in rotational equilibrium.

Question 21

Definition: Moment

Answer 21

The force times perpendicular distance from the pivot.

(Nm)

Question 22

Equation: Work *

Answer 22

ΔW = FΔs

ΔW = increase in work done (J)

F = force applied (N)

Δs = distance moved (m)

Question 23

Equation: Kinetic energy *

Answer 23

Ek = ½mv²

E_k = kinetic energy

m = mass

v = velocity

Question 24

Equation: Gravitational potential energy *

Answer 24

ΔGPE = mgΔh

ΔGPE = change in gravitational potential energy (J)

m = mass (kg)

g = gravity (N kg^-1)

Δh = change in height of centre of gravity (m)

Question 25

What is the relationship between ΔE_grav and ΔE_k?

Answer 25

ΔE_grav = ΔE_k

Question 26

Definition: Principle of conservation of energy

Answer 26

Energy cannot be created or destroyed, just transformed from one form to another.

Question 27

Equation: Average force

Answer 27

F = ΔW / Δs

F = average force (N)

ΔW = work (J)

Δs = distance (m)

Question 28

Definition: Work done

Answer 28

The force times distance moves in the direction of applied force.

(J)

Question 29

What is the relationship between work and energy?

Answer 29

ΔW = Energy

Question 30

Equation: Power *

Answer 30

P = E / t

P = power (W)

E = Energy (J)

t = time (s)

P = W / t

P = power (W)

W = work (J)

t = time (s)

Question 31

Definition: Power

Answer 31

The rate at which work is done (or) the rate at which energy is transferred. (W)

Question 32

Equation: Efficiency *

Answer 32

Efficiency = useful energy output

total energy input

Efficiency = useful power output

total power input