Dynamics

What is mass

A measure of the amount of substance or matter is in an object

What is weight

The gravitational force acting on an object that has mass

What is gravitational field strength

It is the gravitional force acting ong an object per unit mass on an object placed at that point

What is gravitational field

A region which mass experiences a force due to gravitational attraction

What is the difference between mass and weight

Mass is constant regardless of location but weight depends on the gravitational field

What happens when Fnet = 0?

A stationary object remains stationary, a moving object continues moving at a constantly speed in the same direction

What happens when Fnet >0?

A stationary object will move, an object will stop moving, the speed of an object will increase or decrease, an object will change direction

What is inertia

Inertia is the reluctance of a stationary object ti change its state of rest and a moving object to chabge its state of motion

What determines the inertia of an object

Its mass

State which tin takes less effort to move, empty tin A or sand-filled tin B. Explain your answer.

Tin A. It has less mass and less reluctance to change its state of rest to a state of motion.

Why is it dangerous to not wear a seatbelt in a moving car when it comes to a stop

When the car comes to a sudden stoo, you have a reluctance to change your state of motion to a state of rest. hence, you will knock into the front surface of the car and injure yourself.

What is Newtons third law

F by A on B = -F by B on A

What are the characteristics of an action reaction pair

They act on different objects, they are equal In magnitude, they are opposite in direction and they are of the same type

What is the action reaction pair of the the 10N weight of a book resting on the table.

The gravitational force of 10N by the box on the earth towards the box

What is friction

Friction is a contact force that opposes relative motion between two objects that are in contact with one another

What is free fall

When the only force acting on an object is gravity

What is terminal velocity

When the weight of a falling object balances the air resistance

What factors affect the terminal velocty of an object

Its mass, the density of air, its surface area

What is translational equilibrium

It means that the net force is 0 and all the forces are balanced

Using newtons laws of motion, explain why a can attached to a balloon remains motionless in the air

The forces acting on the can are balanced. By newtons first law, the stationary can is in translational equilibrium.

In terms of its magnitude and direction, describe the direction and magnitude of the acceleration of a falling object.

At time t = 0s, its acceleration is 10m/s². From time t= 0.0s to t = 4.0s, the positive acceleration in the downward direction has decreasing magnitude.

Explain in terms of forces acting on the falling object, why the acceleration changes from time to time t = 0.0 to t = 4.0s.

At t = 0.0, the only forces acting on the object is its weight and it accelerates at 10m/s². From t = 0.0 to t = 4.0, air resistance begins to act on the object and increases until it matches the weight of the object. Hence, the net force acting on the object decreases and the acceleration decreases.

Describe the velocity of a ball as it falls at terminal velocity

The balls falls with a constant velocity with no acceleration. The resultant force is zero and hence acceleration is zero.

Describe the motion of the balloon at terminal velocity

Since the total downwards force of the weight cancels the upwards force acting on the balloon, there is not net force acting on the balloon. Its acceleration is zero and its travels upwards at a constant soeed.