Important Equations

Question 1

What is mass?

Answer 1

A measure of the amount of (matter) substance in an object. In grams or kilograms.

Question 2

What is weight?

Answer 2

The force of gravity acting on an object.

Question 3

What is friction?

Answer 3

A force which opposes motion.

Question 4

What is density?

Answer 4

The mass of 1 cm³ of the material.

Question 5

What does Hooke’s Law state?

Answer 5

The extension of a spring is directly proportional to the applied load provided the limit of proportionality is not exceeded.

Question 6

Define pressure?

Answer 6

The force of an object divided by the area of the object in contact with a surface.
P=f/a

Question 7

What is the centre of gravity?

Answer 7

The point on an object where weight appears to act.

Question 8

What is the centre of mass?

Answer 8

The point on an object where all the mass appears to be concentrated.

Question 9

What is a moment?

Answer 9

The product of the force and the perpendicular distance from the pivot to the line of action of the force.

Question 10

What is the principle of moments?

Answer 10

When an object is in equilibrium, the sum of the anticlockwise moments equals the sum of the clockwise moments (ACM=CM) about the same point.

Question 11

Fill in the blank: Weight = _______ X gravity.

Answer 11

[mass]

Question 12

Fill in the blank: Density = _______ ÷ volume.

Answer 12

[mass]

Question 13

Fill in the blank: Force = _______ X extension.

Answer 13

[spring constant]

Question 14

Fill in the blank: Pressure = _______ ÷ area.

Answer 14

[force]

Question 15

Fill in the blank: Moment = _______ X perpendicular distance from pivot.

Answer 15

[force]

Question 16

True or False: Anticlockwise moments equal Clockwise moments in equilibrium.

Answer 16

True

Question 17

What is a scalar quantity?

Answer 17

A scalar quantity has magnitude only.

Examples include temperature and mass.

Question 18

What is a vector quantity?

Answer 18

A vector quantity has both magnitude and direction.

Examples include velocity and force.

Question 19

Define acceleration?

Answer 19

The rate of change of velocity.

Question 20

What does resultant force refer to?

Answer 20

Unbalanced force.

Question 21

State Newton’s First Law of Motion.

Answer 21

An object stays at rest or continues to move in a straight line with constant speed, unless acted on by a resultant force.

Question 22

What is air resistance?

Answer 22

A friction force acting in the opposite direction to the movement of the object.

Question 23

What is the acceleration of free fall?

Answer 23

An object falling freely from rest will accelerate at 10m/s² due to gravity.

Question 24

What is terminal velocity?

Answer 24

The constant velocity reached by a falling object when magnitude of the air resistance force is equal to the magnitude of the weight of the object.

Question 25

State Newton's Second Law of Motion.

Answer 25

The force applied to an object is equal to the mass multiplied by the acceleration.

Question 26

Fill in the blank: Speed = _______ ÷ time.

Answer 26

distance

Question 27

Fill in the blank: Velocity = _______ ÷ time.

Answer 27

displacement

Question 28

What is the formula for average speed?

Answer 28

Average speed = initial speed + final speed/2 Or S= d/t

Question 29

What is the formula for average velocity?

Answer 29

Average velocity = Total displacement ÷ Total time.

Question 30

What is the formula for rate of change of speed?

Answer 30

Rate of change of speed = (final speed - initial speed) ÷ time (V-U/T)

Question 31

What is the formula for acceleration?

Answer 31

Acceleration = final velocity - initial velocity / t

Question 32

What is the formula for resultant force?

Answer 32

Resultant force = mass X acceleration

Question 33

What does the gradient of a distance-time graph represent?

Answer 33

Speed

Question 34

What does the area under a velocity-time graph represent?

Answer 34

Displacement

Question 35

What is the relationship between velocity and time in a velocity-time graph?

Answer 35

Acceleration

Question 36

What does the gradient of a velocity-time graph indicate?

Answer 36

Rate of change of speed

Question 37

Fill in the blank: Speed is represented on a _______ graph.

Answer 37

Speed - Time

Question 38

True or False: The area under a distance-time graph represents acceleration.

Answer 38

False

Question 39

Newtons 3rd Law

Answer 39

When objects interact with each other, they always have an equal and opposite reaction