Dynamics

Question 1

Formula for force

Answer 1

Force = mass x acceleration

Question 2

State Newtons 1st law of motion

Answer 2

1) An object will stay at rest or continue to move with constant velocity unless there is a resultant force

Question 3

State Newtons 2nd law of motion

Answer 3

2) Force = mass x acceleration

Question 4

State Newtons 3rd law of motion

Answer 4

3) For every action there is an equal but opposite reaction

Question 5

Formula for weight

Answer 5

Weight = mass x gravity

Question 6

What is the gravity on earth?

Answer 6

10m/s^2

Question 7

What is the gravity on the moon?

Answer 7

1.67m/s^2

Question 8

What is air resistance?

Answer 8

The force that exists when an object moves in air.

It always opposes motion

Question 9

What is normal reaction?

Answer 9

Exists between 2 objects which are in contact. It is opposite to weight. Normal reaction = weight

Question 10

What is tension?

Answer 10

A force that exists in a rope or a spring

Question 11

What is upthrust?

Answer 11

The upward force that water exerts on an object

Question 12

What is inertia?

Answer 12

The reluctance of an object at rest to move or a moving object to stop

Question 13

What is frictional force?

Answer 13

The force that exists between a moving object and its surface of contact. It opposes motion

Question 14

What does frictional force produce?

Answer 14

Friction between 2 surfaces produces heat

Question 15

How does friction help slow down a vehicle when brakes applied?

Answer 15

The brake pads are made to come in contact with a metal disc fixed to the wheels. Frictional force is produced between the brake pads and the metal disc that causes the vehicle to decelerate

Question 16

How is a vehicle able to turn a corner?

Answer 16

Because there is frictional force acting on the surface of each tyre in contact with the road. If friction is low then the vehicle will skid.

Question 17

What is centripetal force?

Answer 17

The force acting on an object undergoing circular motion, it is always directed towards the centre of the circular path

Question 18

Where does the velocity of an object with centripetal force act?

Answer 18

Along the tangent of the circle where the object is found

Question 19

An object moves at a constant speed along a circle. Explain why there is centripetal force although the speed is constant

Answer 19

Since the direction of velocity is changing, there is acceleration. Therefore there is a force

Question 20

Examples of centripetal force (2)

Answer 20

1) The gravitational force acting on a satellite orbiting the earth
2) The electrostatic forces acting on electrons orbiting the nucleus