AQA GCSE Physics (Triple) - Paper 2: Forces

These flashcards cover key concepts and definitions from the AQA GCSE Physics (Triple) Paper 2 on Forces, assisting in review and memorization in preparation for the exam.

What is a scalar quantity?

A quantity that has magnitude only, e.g., speed, distance, mass, time.

What is a vector quantity?

A quantity that has both magnitude and direction, e.g., velocity, force, displacement.

Give examples of contact forces.

Friction, air resistance, tension, and normal contact force.

Give examples of non-contact forces.

Gravitational, magnetic, and electrostatic forces.

What is the weight of an object?

The force acting on it due to gravity; it depends on mass and gravitational field strength.

What is the formula for weight?

Weight (N) = Mass (kg) × Gravitational field strength (N/kg).

What is the difference between mass and weight?

Mass is the amount of matter in an object; weight is the force due to gravity acting on it.

What is meant by the resultant force?

The single force that has the same effect as all the individual forces acting on an object.

What happens when the resultant force is zero?

The object is at rest or moving at a constant velocity.

What happens when there is a non-zero resultant force?

The object accelerates in the direction of the resultant force.

What is work done?

The energy transferred when a force moves an object through a distance in the direction.

What is the formula for work done?

Work done (J) = Force (N) × Distance moved (m).

What is the relationship between work and energy transfer?

Work done is equal to the energy transferred to or from an object by a force.

What is Hooke’s Law?

The extension of a spring is directly proportional to the force applied, provided the limit of proportionality is not exceeded.

What happens when a spring exceeds its limit of proportionality?

It no longer obeys Hooke’s Law, and the extension is no longer proportional to the force.

What is meant by elastic deformation?

The object returns to its original shape when the force is removed.

What is inelastic deformation?

The object is permanently deformed after the force is removed.

What is a moment of a force?

The turning effect of a force around a pivot.

What is the formula for the moment of a force?

Moment (Nm) = Force (N) × Perpendicular distance from pivot (m).

What is meant by the principle of moments?

For an object in equilibrium, the total clockwise moments equal the total anticlockwise moments.

How do levers make work easier?

They increase the distance from the pivot, reducing the force needed to achieve the same moment.

What are gears used for?

To transmit the rotational effect of a force; larger gears turn slower but with more moment.

What is pressure?

The force exerted per unit area.

What is the formula for pressure?

Pressure (Pa) = Force (N) ÷ Area (m²).

How does pressure in a fluid change with depth?

Pressure increases with depth due to the weight of the fluid above.

What is upthrust?

The upward force that a fluid exerts on a submerged object.

What determines whether an object floats or sinks?

If the upthrust equals the object's weight, it floats; if weight is greater, it sinks.

What does Newton’s First Law state?

An object will remain at rest or move at a constant velocity unless acted upon by a resultant force.

What does Newton’s Second Law state?

The acceleration of an object is directly proportional to the resultant force and inversely proportional to its mass.

What does Newton’s Third Law state?

When two objects interact, they exert equal and opposite forces on each other.

What factors affect thinking distance?

Reaction time, which depends on tiredness, drugs, alcohol, and distractions.

What factors affect braking distance?

Speed, road conditions, tyre condition, and brake efficiency.

What is momentum?

The product of an object’s mass and velocity (p = mv).

What does conservation of momentum mean?

In a closed system, the total momentum before an event equals the total momentum after.

What is inertia?

The tendency of an object to continue in its state of rest or uniform motion unless acted upon by an external force.

What is terminal velocity?

The constant speed reached by an object when the resistive forces balance the driving forces.

Why does an object accelerate at first when falling?

Because the weight is greater than air resistance.

Why does an object stop accelerating and reach terminal velocity?

Air resistance increases until it balances the weight, making the resultant force zero.

What is drag?

The resistive force acting opposite to the motion of an object moving through a fluid.

How can drag be reduced?

By streamlining shapes to reduce air or fluid resistance.

What happens to kinetic energy when work is done against friction?

It is transferred to thermal energy, heating the surfaces and surroundings.

What is pressure in a gas caused by?

Particles colliding with the walls of the container, exerting a force per unit area.

How does temperature affect gas pressure?

Increasing temperature increases the speed of particles, leading to more frequent collisions with the walls.

Why do astronauts experience weightlessness?

They are in free fall, accelerating towards Earth at the same rate as their spacecraft.

What does a flat line on a distance–time graph represent?

The object is stationary.

What does a straight, sloping line on a velocity–time graph represent?

Constant acceleration.

How is the acceleration of an object represented on a velocity–time graph?

By the gradient of the line.