2. Mechanics

Question 1

Instantaneous speed

Answer 1

The speed of an object at an instant in time; the rate of change of position with respect to time.

Question 2

Average speed

Answer 2

the average speed over the whole journey = total distance/total time

Question 3

Acceleration

Answer 3

The rate of change of velocity with respect to time.

Question 4

Air resistance

Answer 4

The transfer of energy into the fluid from an object moving in it.

Question 5

Translational equilibrium

Answer 5

When there is no resultant force acting on an object and therefore it is stationary or moving at a constant velocity.

Question 6

Newton’s first law of motion

Answer 6

An object continues to remain stationary or to move at a constant velocity unless an external force acts on it.

Question 7

Inertia

Answer 7

The property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

Question 8

Newton’s second law of motion

Answer 8

force = mass * acceleration

Question 9

Newton’s third law of motion

Answer 9

Every action has an equal and opposite reaction.

Question 10

Static friction

Answer 10

the friction when there is no relative movement between the surfaces.

Question 11

Dynamic friction

Answer 11

the friction when there is relative movement between the surfaces.

Question 12

Kinetic energy

Answer 12

the energy an object has because of its motion.

Question 13

Gravitational potential energy

Answer 13

the energy an object has because of its position in a gravitational field.

Question 14

Elastic potential energy

Answer 14

energy stored as a result of the deformation of an elastic object/the work done to stretch the spring.

Question 15

Work done

Answer 15

force exerted * distance moved in the direction of the force

Question 16

Power

Answer 16

the rate of energy transfer

Question 17

Principle of conservation of energy

Answer 17

energy cannot be created or destroyed, only transferred form one form to another.

Question 18

Momentum

Answer 18

the product of the mass of the object and its instantaneous velocity.

Question 19

Impulse

Answer 19

change in momentum = force*t

Question 20

Collision

Answer 20

an interaction where momentum transfers.

Question 21

Principle of conservation of momentum

Answer 21

Momentum is always constant if no external force acts on a system.

Question 22

Elastic collision

Answer 22

A collision where kinetic energy is conserved.