CIE IGCSE Physics (0625) - Forces and their effects

Question 1

What does mass measure?

Answer 1

The amount of matter in an object, measured in kilograms (kg).

Question 2

What does weight measure?

Answer 2

The force of gravity acting on a mass, measured in newtons (N).

Question 3

What is the unit of mass?

Answer 3

Kilogram (kg), the SI unit for mass.

Question 4

What is the unit of weight?

Answer 4

Newton (N), the SI unit for weight.

Question 5

What is the equation linking weight, mass and gravitational field strength?

Answer 5

W = m × g

Question 6

What is the value of g (gravitational field strength) on earth?

Answer 6

9.8 N/kg

Question 7

How are mass and weight different?

Answer 7

Mass is a measure of matter; weight is the force of gravity on that mass.

Question 8

What is inertia?

Answer 8

The tendency of an object to remain at rest or in uniform motion.

Question 9

How can a force change an object?

Answer 9

It can change its size or shape.

Question 10

What is the equation for hooke’s law?

Answer 10

F = k × x

Question 11

What is k in hooke’s law?

Answer 11

The spring constant, measured in N/m.

Question 12

What is the elastic limit?

Answer 12

The limit in which a spring behaves elastically and returns to its original length after an applied load is removed. Beyond this point, it becomes permanently stretched.

Question 13

How do you calculate extension?

Answer 13

Extension = stretched length − original length

Question 14

What graph is used in a spring experiment?

Answer 14

Extension–load graph

Question 15

What should be plotted on the y-axis of an extension–load graph?

Answer 15

Extension (m)

Question 16

What should be plotted on the x-axis of an extension–load graph?

Answer 16

Force (N)

Question 17

What does the gradient of an extension–load graph represent?

Answer 17

The gradient is 1 ÷ k, so the spring constant k is the inverse of the gradient.

Question 18

What is a resultant force?

Answer 18

The overall force after combining all forces acting on an object.

Question 19

What happens when forces act in the same direction?

Answer 19

They are added together.

Question 20

What happens when forces act in opposite directions?

Answer 20

They are subtracted.

Question 21

What is the rule for finding the resultant of two forces at right angles?

Answer 21

Use a scale vector diagram and measure the diagonal, or apply Pythagoras’ theorem to find the magnitude of the resultant force.

Question 22

What does newton’s first law state?

Answer 22

An object stays at rest or moves at constant speed unless a resultant force acts.

Question 23

What is Newton’s Second Law?

Answer 23

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass: F = ma.

Question 24

What does a resultant force do?

Answer 24

It can cause acceleration, deceleration, or a change in direction.

Question 25

What is the equation linking force, mass, and acceleration?

Answer 25

F = m × a

Question 26

What is the unit of acceleration?

Answer 26

m/s²

Question 27

What is friction?

Answer 27

A contact force that acts in the opposite direction of motion between two surfaces.

Question 28

What is air resistance?

Answer 28

A frictional force caused by air particles hitting a moving object.

Question 29

What is drag?

Answer 29

Friction acting on an object moving through a fluid (liquid or gas).

Question 30

What is centripetal force?

Answer 30

The force that keeps an object moving in a circular path.

Question 31

What does centripetal force depend on?

Answer 31

Mass, speed, and radius of the circle.

Question 32

In circular motion, which direction does the centripetal force act?

Answer 32

Towards the centre of the circle.

Question 33

How can an object moving at constant speed still accelerate?

Answer 33

If its direction is changing, its velocity is changing — so it is accelerating even if its speed is constant.

Question 34

Does the speed change in uniform circular motion?

Answer 34

No, only the direction changes.

Question 35

What is the equation for centripetal force?

Answer 35

Centripetal force = (mass × speed²) ÷ radius or F = mv² ÷ r