Forces, motion and momentum

On a displacement time graph, what is the gradient?

Velocity

On a velocity time graph, what is gradient?

Acceleration

On a velocity time graph, what is the area under the graph?

Total displacement

What is Newton’s first law of motion?

A body will remain at rest or continue to move with constant velocity unless acted upon by a resultant force.

What is Newton’s second law of motion?

The rate of change of momentum of an object is directly proportional to the resultant force and takes place in the direction of the force.

What is Newton’s third law of motion?

When two objects interact, each exerts an equal but opposite force on the other during the interaction.

These forces are both the same type of force.

What equation do we use to explain Newton’s second law of motion?

F = delta P / delta t

When can we use F = ma for Newton’s second law of motion?

When the mass of the object remains constant during the period of acceleration.

What is a vector quantity?

A quantity with both magnitude and direction.

What is a scalar quantity?

A quantity with magnitude but not direction.

What is the stopping distance of a vehicle?

The total distance travelled between the moment when the driver first sees a reason to stop, to when the vehicle stops.

What is the thinking distance?

The distance travelled between the moment when you first see a reason, to stop to the moment when you use the brake.

What is the braking distance?

The distance travelled from the time the brake is applied until the vehicle stops.

How can a plumb line determine an objects centre of mass?

Let the object swing freely to come to rest.

Its centre of mass will be directly below where it is hanging from to draw a vertical line down from where it’s hanging from.

Repeat this for multiple point and see where the line intersect.

This is the objects centre of mass.

What is the principle of moments?

For a body in rotational equilibrium, the sum of the anti-clockwise moments about any point is equal to the sum of the clockwise moments about that same point.

What is the moment of a force?

Moment = Force x Perpendicular distance of the line of action of force from the axis or point of rotation.

m = Fx

What is a couple?

A pair of equal but opposite parallel forces acting on an object at different points, creating a moment whilst the net force is zero.

What is the moment of a couple?

A torque.

What is the equation of the moment/torque of a couple?

Torque = One of the forces x perpendicular separation between the forces.

Torque = Fd

What is Archimedes principle?

The upthrust exerted on a body immersed in a fluid is equal to the weight of fluid displaced.

What are the four fundamental forces?

Gravitational.

Electromagnetic.

Weak nuclear.

Strong nuclear.

What is the principle of conservation of momentum?

Total momentum of a system remains the same before and after the collision.

What is a perfectly elastic collision?

A collision where the total kinetic energy is conserved.

What is an inelastic collision?

A collision where the total kinetic is not conserved.