Physics - Dynamics - A levels

Free body diagram

Objects that are represented as point particles placed at the center of a mass

Define the term of resultant force

It is the vector sum of all the forces when exerted in an object

Do free body diagrams show forces acting on multiple objects?

No, it only show forces that act on only one system or one object

State two quantities that a force arrow represents

Magnitude and direction

When forces are balanced, do they produce non zero resultant force?

No, they produce zero resultant force

When two forces in different planes act on an object, how can the resultant force be found

by using trigonometry, pythagoras theorem , and vector diagrams

An object moving in a constant velocity has no resultant force acting on it

True

Define Newton’s first law of motion

An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by a net external force.

Define the term translational equilibrium

A state where the sum of all forces and the sum of all moments acting on an object are zero, resulting in no acceleration.

What are three ways resultant force can change an object’s motion?

By speeding it up, slowing it down and changing its direction.

Define Newtons’ second law of motion

The acceleration of an object is directly proportional to the net external force acting on it and inversely proportional to its mass, expressed by the formula F=ma.

Acceleration always act in the same direction as the resultant force

True, acceleration always act in the same direction as the resultant force

If no drag forces are present, then the acceleration of the falling object is independent of its mass

True, it is independent to its mass

State Newton’s second law of motion in terms of momentum

the resultant force is equal to the change in momentum

Newtons’ first and second law of motion can involve multiple forces acting on on object

True

Newton’s third law of motion involves two object exerting the same type of force on each other

False, it involves only one object exerting the same type of force on each other

Define Newton’s third law of motion

If one body exerts a force on another body, the second body will exert force on the first body, which is equal in magnitude and opposite direction.

the four characteristics of a newton’s third law force pair

1. the same type of force

2. equal in magnitude

3. opposite in direction

4. act on different objects

Weight and normal contact force are an example of a third law pair

No, they act on the same object and are not the same type of force

Define contact force

contact force is defined a a force that acts between objects that are physically in contact

Give an example of contact force

Tension, surface friction, drag, reaction force

What is surface friction

It is a force that opposes the motion of an object moving over a surface

What is tension force?

Tension force is a force that occurs within an object when a pulling force is applied to both ends

what is a Normal reaction force?

It is when the component of the contact force is perpendicular to the surface

What is a non contact force?

It is the force which acts at a distance without physical contact due to the action of the field

State an example of a non-contact force

Gravitational force, electrostatic force and magnetic force

What is gravitational force?

It is the attractive force experienced by two objects with mass in a gravitational field

Is surface friction allows parallel to the plane of contact?

Yes, it is indeed parallel to the plane of contact