Mechanics

Question 1

Momentum

Is it scalar or vector?

Answer 1

Vector

Question 2

What is impulse?

Answer 2

Change in momentum

Question 3

What is Torque?

Answer 3

The total moment of a couple

Question 4

What is the unit for momentum?

Answer 4

Kgms^-1

Question 5

Define moment

Answer 5

The product of the force and the perpendicular distance from the point of action of the force to the axis of rotation

Question 6

What happens in a partially elastic collision?

Answer 6

The objects move apart but have less kinetic energy than before

Question 7

In projectile motion what happens in the vertical and horizontal directions?

Answer 7

In the horizontal there is no force on the object and therefore doesn’t accelerate.
In the vertical the object accelerates under gravity

Question 8

Average velocity = ?

Answer 8

Displacement change/ time taken

Question 9

Define displacement

Answer 9

The length and direction of the straight line drawn from an objects initial position

Question 10

What does the gradient give you in a velocity-time graph?

Answer 10

The acceleration

Question 11

In a velocity-time graph, what does the area under the graph give you?

Answer 11

The distance/displacement

Question 12

What is Newton’s second law of motion?

Answer 12

The acceleration of a body of constant mass is related to the net external resultant force acting on the body by the equation: resultant force = m x a

Question 13

Define inertia

Answer 13

The tendency of an object to remain in its state of rest or uniform motion in a straight line

Question 14

Define centre of gravity

Answer 14

The single point in an object where all the weight appears to act

Question 15

Define a couple

Answer 15

A pair of equal and opposite forces acting on a body, but not along the same line

Question 16

Define acceleration

Answer 16

Change of velocity per unit time

Question 17

What does the gradient of a the line in a distance-time graph give us?

Answer 17

The speed

Question 18

What is Newton’s first law of motion?

Answer 18

A body will remain at rest or move with a constant velocity unless it is acted on by a net external resultant force

Question 19

Define instantaneous velocity

Answer 19

The rate of change of velocity with time

Question 20

What happens in a totally inelastic collision?

Answer 20

The objects stick together

Question 21

Average acceleration equals what?

Answer 21

velocity change / time taken.

Question 22

Define instantaneous velocity

Answer 22

The rate of change of displacement with time

Question 23

Define distance

Answer 23

The length of the path moved by an object

Question 24

Average speed equals what?

Answer 24

distance change / time taken

Question 25

Define instantaneous speed

Answer 25

The rate of change of distance with time

Question 26

What happens in an elastic collision?

Answer 26

No kinetic energy is lost.

Question 27

Define acceleration of free fall

Answer 27

Acceleration of an object acted on only by the force of gravity.

Question 28

What is the equation for momemtum?

Answer 28

m x v

Question 29

What is represented by the area under a force-displacement graph?

Answer 29

Work done

Question 30

What is the principle of conservation of momentum?

Answer 30

The total momentum of a system is constant provided there is no external force on the system.

Question 31

Why is the time for an object to free fall independent of the object’s mass?

Answer 31

Force on an object = mg and acceleration = F/m = mg/m = g

Time to fall depends only on the distance and the acceleration.