Summary Notes - Topic 1 Forces and Motion - Edexcel Physics IGCSE

Question 1

What is speed defined as?

Answer 1

Distance travelled per unit time.

Question 2

What does it mean if the speed of something is changing?

Answer 2

It is accelerating or decelerating.

Question 3

What is the acceleration of free fall near to the Earth?

Answer 3

Constant.

Question 4

What is the formula for average speed?

Answer 4

Average speed = total distance / total time.

Question 5

How is velocity defined?

Answer 5

Speed in a given direction.

Question 6

What is the definition of acceleration?

Answer 6

Change in velocity per unit time.

Question 7

What is the formula for acceleration?

Answer 7

Acceleration = change in velocity / time taken.

Question 8

What does the equation (final speed)² = (initial speed)² + (2 × acceleration × distance) represent?

Answer 8

A kinematic equation relating speed, acceleration, and distance.

Question 9

What units are used for distance, time, speed, velocity, and acceleration?

Answer 9

• Distance: metres (m) * Time: seconds (s) * Speed/Velocity: metres per second (m/s) * Acceleration: metres per second squared (m/s²)

Question 10

In a displacement-time graph, what does a horizontal line indicate?

Answer 10

The object is stationary.

Question 11

What does a negative gradient in a displacement-time graph indicate?

Answer 11

The object is returning back to the starting point.

Question 12

In a velocity-time graph, what does the gradient represent?

Answer 12

Acceleration.

Question 13

What does a curved line in a velocity-time graph indicate?

Answer 13

The acceleration is changing.

Question 14

What is a vector?

Answer 14

A quantity that has both magnitude and direction.

Question 15

What is a scalar?

Answer 15

A quantity that has only magnitude.

Question 16

Give examples of scalars.

Answer 16

• Distance * Speed * Time * Energy

Question 17

Give examples of vectors.

Answer 17

• Displacement * Velocity * Acceleration * Force

Question 18

What can forces change in a body?

Answer 18

• Speed * Shape * Direction

Question 19

What is friction?

Answer 19

A force between two surfaces that impedes motion and results in heating.

Question 20

What is Newton’s first law?

Answer 20

An object has a constant velocity unless acted on by a resultant force.

Question 21

What is Newton’s second law?

Answer 21

Force = mass × acceleration (F = ma).

Question 22

What does Newton’s third law state?

Answer 22

Every action force has an equal and opposite reaction force.

Question 23

How is weight defined?

Answer 23

Weight is a gravitational force acting on a mass.

Question 24

What is the formula for weight?

Answer 24

Weight = mass × gravitational field strength (W = mg).

Question 25

What is the gravitational field strength on Earth?

Answer 25

10 N/kg.

Question 26

What is terminal velocity?

Answer 26

The constant speed reached when the force of gravity is balanced by air resistance.

Question 27

What factors increase thinking distance?

Answer 27

* Greater speed * Slower reaction time due to alcohol, tiredness, or distractions.

Question 28

What factors increase braking distance?

Answer 28

* Greater speed or mass * Poor road conditions (icy, wet) * Poor car conditions (worn tires, worn brake pads)

Question 29

What is stopping distance?

Answer 29

The sum of thinking distance and braking distance.

Question 30

What is elastic deformation?

Answer 30

When an object returns to its original shape after the load is removed.

Question 31

What does Hooke's law state?

Answer 31

For a spring, F = kx, where F is the force, k is the spring constant, and x is the extension.

Question 32

What is the limit of proportionality?

Answer 32

The point beyond which a material no longer obeys Hooke's law.

Question 33

What is the formula for moment?

Answer 33

Moment = force × perpendicular distance from the pivot (moment = Fd).

Question 34

What condition must be met for an object to be in equilibrium?

Answer 34

The sum of clockwise moments equals the sum of anticlockwise moments.

Question 35

What is momentum?

Answer 35

The product of mass and velocity (momentum = mass × velocity, p = mv).

Question 36

How is force related to momentum?

Answer 36

Force = change in momentum / time taken.

Question 37

What is the principle of conservation of momentum?

Answer 37

The total momentum before a collision is equal to the total momentum after the collision.

Question 38

In a collision involving a gun and bullet, what is the total momentum before firing?

Answer 38

Zero.

Question 39

What is the recoil speed of a gun if a 10kg stationary gun fires a 0.01kg bullet at 100m/s?

Answer 39

-0.1 m/s.