Chapter 9: Forces and motion

Question 1

9A:

Define a “Force.”

Answer 1

A push or pull of an object associated with both a magnitude and a direction, being expressed in Newtons.

Question 2

9A:

Define the term “Net force.”

Answer 2

The net force of an object refers to the vector sum of all the forces acting on an object.

Question 3

9A:

Describe Newton’s first law

Answer 3

Newton’s first law states that an object will only accelerate if a non-zero net force acts upon it. Otherwise, the object will maintain a constant velocity/motion.

Question 4

9A:

Describe Newton’s second law

Answer 4

Newton’s second law states that the net force acting on an object is proportional to that object’s mass and acceleration, with the acceleration of an object being inversely proportional to its mass.

Question 5

9A:

Describe Newton’s third law

Answer 5

Newton’s third law states that there will be a reaction force in the opposite direction of the same magnitude for every action force.

Question 6

9A:

Describe the gravitational force

Answer 6

The gravitational force is a force experienced by an object due to the gravitational field of another object.

Question 7

9A:

Describe the Normal force

Answer 7

A force that acts on an object in contact with the surface of another object at a right angle to the point of contact is referred to as the “Normal force.”

Question 8

9B:

Describe the meaning of an “Isolated system.”

Answer 8

An Isolated system is just a collection of objects which has no external exchange of mass or energy.

Question 9

9B:

Describe the “Conservation of momentum.”

Answer 9

The conservation of momentum states that the total momentum of an isolated system is always conserved, regardless of any collisions that occur within that isolated system between its objects.

: The total momentum of a system is found by summing the individual momentum of each object within the wider system.

Question 10

9B:

Define the term “Impulse.”

Answer 10

An impulse describes the change in momentum which an object undergoes as a result of a change in velocity. This change in velocity occurs due to an unbalanced force acting on that object over time.

Question 11

9D:

Define an “Inclined plane.”

Answer 11

Any flat surface which is at an angle to the horizontal is known as an inclined plane.

Question 12

9D:

Define a “Connected body.”

Answer 12

A connected body describes two objects/bodies which are either in direct contact or in connection via a string or any other similar connection.

Question 13

9D:

Define the “Tension force.”

Question 14

9E:

Define the term “Torque.”

Answer 14

A torque is a turning effect or a rotational motion yielded when a force acts at a perpendicular distance from a pivot point.

Question 15

9F:

When is a system in equilibrium?

Answer 15

A system is in equilibrium when it is in both transnational and rotational equilibrium.

Question 16

9F:

Define the term “Transnational equilibrium.”

Answer 16

This describes when the net force acting on a system is equal to zero, meaning its linear acceleration is also equal to zero.

Also, this means that the net force vertically and horizontally are both equal to zero for that object.

Question 17

9F:

Define the term “Rotational equilibrium.”

Answer 17

This describes when the net torque acting on a system is equal to zero. Here, the clockwise torque is equal in magnitude to the anticlockwise torque.

This means the rotational acceleration of an object is equal to zero.