Forces and Energy Exam Notes (copy)

What is a force?

A force is a push, pull, or twist that can change the shape, size, or motion of an object.

What is the unit of force?

The unit of force is Newtons (N).

What does the net force on an object represent?

The net force acting on an object is the sum of all forces acting upon it.

What happens if the net force is zero?

If the net force is zero, the object's motion does not change; it remains at rest or continues moving at a constant velocity.

What is Newton's First Law?

An object resists changes to its motion; it will remain at rest or move at a constant velocity unless acted upon by a net force.

What is the equation of Newton's Second Law?

The relationship is given by the formula: F_net = ma, where F is force, m is mass, and a is acceleration.

What does Newton's Third Law state?

Every action force has an equal and opposite reaction force.

What is friction?

Friction is the force between two surfaces moving or intending to move against each other.

What does Hooke's Law state?

The extension of a stretched spring is directly proportional to the load or force applied, represented as F = kx.

What is a moment in physics?

A moment is a measure of a force's turning effect about a pivot.

What is the principle of moments?

If an object is balanced, then total anticlockwise moments equal total clockwise moments.

What is the center of gravity?

The center of gravity is the point where the entire mass of an object is thought to be concentrated.

What are the seven energy stores?

1. Kinetic, 2. Gravitational Potential, 3. Chemical, 4. Elastic, 5. Nuclear, 6. Electrostatic, 7. Internal (Thermal).

What is the conservation of energy?

Energy can neither be created nor destroyed, only transformed from one form to another.

How is efficiency calculated?

Efficiency = (useful energy output / total energy input) × 100%.

What happens when an object is lifted in a gravitational field?

Energy is transferred to its gravitational potential energy store.

What are non-renewable energy resources?

Energy resources that cannot be replenished at the rate they are consumed, such as fossil fuels.

What is tidal power?

Tidal power generates electricity using the gravitational effects of the moon and sun on ocean tides.

How is power defined in physics?

Power is the measure of how quickly work is being done, calculated as Power = Energy transferred / Time taken.