First term Physics

What is a force?

This is a push or pull that when exerted causes a change in an object’s position, shape, size, or direction

What is the SI unit of force?

Newton (N)

What are the two types or categories of force?

Contact and non-contact force

What is a contact force?

This is a force that is exerted when objects are in physical contact.

What are the types of contact forces?

1. Applied force

2. Friction

3. Tension

4. Upthrust

What is an applied force?

This is a force that one object applies to another

What is friction?

This is the restrictive force exerted on objects as they move across each other. It prevents the movement of objects which results in the production of heat.

What is tension?

This is the force exerted along a rope, string, or spring as it is pulled tightly.

Define the term upthrust

This is the force exerted by a fluid on an object whether it is partially or fully submerged in the fluid.

What is a non-contact/force at a distance?

This is a force exerted by objects that are not in physical contact

What are the non contact forces?

1. Gravitational force

2. Magnetic force

3. Electrostatic force

4. Nuclear force

What is a gravitational force?

This is the force exerted by all objects of mass on other objects.

What is a magnetic force?

This is the force exerted between magnetic forces

What is electrostatic force?

This is the force exerted by charged objects

What is a nuclear force?

This is the force exerted by charged particles inside the nucleus of the atom.

What is a vector quantity?

This is a physical quantity having both magnitude and direction. Examples include Acceleration, Velocity, Force, Momentum, Displacement

What is a resultant/net force?

This refers to the net effect of multiple forces acting on a system.

What are parallel vectors?

These are vectors that are in the same or exact opposite direction

What is an antiparallel vector?

This is a vectors that is parallel in nature but opposite in direction

What is Acceleration?

This is the rate of change of Velocity of an object

What is the formula for Acceleration?

a=F/m

What is a Newton?

This is the force required to cause a 1Kg mass to be accelerated by 1 m/s²

What is mass?

This is the amount of particles that make up an object.

What is the SI unit for mass?

Kilogram

Define the term weight

This is the force exerted on an object due to it being in a gravitational field

What is the SI unit for weight?

Newton (N)

What is the formula for weight?

W=m×g

What does the symbol ‘g‘ mean?

Gravitational field strength which is measured in N/Kg or m/s²

What is a gravitational field ?

This is a region in which a mass experiences a force. It can be described by its gravitational field strength (g)

What is gravitational field strength?

This is the force exerted on a 1kg mass due to a gravitational field.

What is the SI unit for gravitational field strength?

N/Kg

What is the value of Earth’s gravitational field strength?

10 N/Kg

What is the center of gravity?

This is the point on an object where the force of gravity is concentrated

Where does the weight of an object usually act through?

It usually acts through its center of gravity.

Where is the centre of gravity for a uniform object located?

At its geometric center.

Where is the centre of gravity of a non-uniform object located?

This is located at a point other than its geometric centre

How is the centre of gravity of an irregularly shaped object located?

By using the plum line method

1. Set up apparatus

2. Make a hole at a convenient point near the edge of the lamina

3. Suspend the lamina from the hole and allow it to swing freely

4. Attach the plumb line and mark on the opposite edge where the plum line touches the paper

5. Draw a straight line from the hole to the point

6. Repeat steps 2-4 for another 2 holes.

Define the term stability

This is the ability of an object to resist being toppled over.

What determines the stability of an object?

The position of the centre of gravity and the width of the base

What are the types of equilibrium positions?

Stable, unstable and neutral equilibrium

What does it mean when an object is in stable equilibrium?

An object is in stable equilibrium if it returns to its original position after being slightly displaced

What does it mean when an object is in unstable equilibrium?

An object is in unstable equilibrium if it does not return to its original position after being slightly displaced

What does it mean when an object is in neutral equilibrium?

An object is in neutral equilibrium if it attains a new equilibrium position after being slightly displaced. In other words it stays in its new position when displaced.

Define the term moment

This is a turning effect due to a force about a fixed point (pivot).

What is the formula for finding the moment of a force?

T= F×d

What is the moment of a force?

This is the product of the force and the perpendicular distance from the line of action of the force and the pivot.

What does the principal of moment state?

This states that for a system in equilibrium the sum of the clockwise moments about any fixed point is equal to the sum of the anti-clockwise moment about that same point. (£CWT=£ACWT)

What is the formula for finding the moment in regards to clockwise and anticlockwise moments?

What does the hooks law state?

This law state that the extension of a spring is directly proportional to the force applied provided the proportional limit is not exceeded.

What is the formula for hooke's law?

F= Ke