1. Forces and their Effect

Question 1

What are the two main types of forces that objects interact by?

Answer 1

Objects interact by non-contact (field) forces and contact forces.

Question 2

How can the speed of an object be calculated from a distance-time graph?

Answer 2

The speed of an object can be calculated from the gradient of a distance-time graph.

Question 3

What does Newton’s Third Law state?

Answer 3

Newton’s Third Law states that whenever two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction.

Question 4

What does Newton’s Second Law state?

Answer 4

The acceleration of an object is proportional to the resultant force on the object and inversely proportional to the mass of the object.

Question 5

What does Newton’s First Law state?

Answer 5

If the resultant force on an object is 0, the object stays at rest if it is stationary, or it keeps moving with the same speed in the same direction.

Question 6

What is momentum?

Answer 6

Momentum is the product of an object’s mass and velocity.

Question 7

What factors affect the stopping distance of a vehicle?

Answer 7

The stopping distance of a vehicle is affected by the driver’s reaction time (thinking distance) and the distance it travels under the braking force (braking distance).

Question 8

What happens to the resultant force when an object reaches terminal velocity?

Answer 8

When an object reaches terminal velocity, the resultant force becomes zero.

Question 9

What is the center of mass of an object?

Answer 9

The center of mass of an object is the point at which the mass of the object may be thought to be concentrated.

Question 9

What is the relationship between moment, turning force, and perpendicular distance?

Answer 9

The relationship between moment, turning force, and perpendicular distance is: Moment = Turning Force × Perpendicular Distance.

Question 10

Give examples of non-contact forces

Answer 10

Examples include gravity, electrostatics, and magnetism.

Question 11

What are examples of contact forces?

Answer 11

Examples include friction, air resistance, tension, and normal contact force.

Question 12

Define velocity.

Answer 12

Velocity is the speed of an object in a given direction. (Vector quantity)

Question 13

Define acceleration.

Answer 13

Acceleration is the rate of change of velocity.

Question 14

Describe the law of conservation of momentum.

Answer 14

The total momentum of a closed system remains constant before and after a collision.

Question 15

What happens if the resultant force acting on an object is zero?

Answer 15

A moving object will continue to move at the same velocity, and a stationary object will remain at rest.

Question 16

Define terminal velocity.

Answer 16

Terminal velocity is the velocity reached by an object when the drag force is equal and opposite to the force making it move

Question 17

How do parachutes work?

Answer 17

Parachutes increase drag force, reducing terminal velocity.

Question 18

How does the position of the center of mass affect the stability of an object?

Answer 18

The lower the center of mass, the more stable the object.

Question 19

What is a moment?

Answer 19

A moment is the turning effect of a force.

Question 19

What are scalar quantities?

Answer 19

Scalar quantities are physical quantities that have magnitude only.

Question 20

Give examples of scalar quantities.

Answer 20

Examples include distance, speed, time, mass, and temperature.

Question 21

What are vector quantities?

Answer 21

Vector quantities are physical quantities that have both magnitude and direction.

Question 22

Give examples of vector quantities.

Answer 22

Examples include displacement, velocity, acceleration, force, and momentum.

Question 23

What is the relationship between force, change in momentum, and time.

Answer 23

Force = change in momentum/time

Question 24

Where is the center of mass on a symmetrical object?

Answer 24

The center of mass of a symmetrical object is along the axis of symmetry. The position of the center of mass affects the stability of objects.

Question 25

State the Principle of Moments.

Answer 25

If an object is not turning, the total clockwise moment must be exactly balanced by the total anticlockwise moment about any pivot.

Question 26

What happens if the line of action of the weight of an object lies outside the base of the object?

Answer 26

If the line of action of the weight of an object lies outside the base of the object, there will be a resultant moment, and the body will topple.