Force And Motion

Question 1

What equation links resultant force, mass and acceleration?

Answer 1

Resultant force = mass x acceleration

Question 2

What is Newton’s second law of motion?

Answer 2

The acceleration of an object is proportional to the resultant force on the object.
The acceleration of an object is inversely proportional to the mass of the object.

So the resultant force is proportional to the objects mass multiplied by its acceleration.

Question 3

What is inertia?

Answer 3

The tendency of an object to stay at rest or continue in uniform motion. Eg moving at constant velocity. The inertial mass of an object is a measure of the difficulty of changing the object’s velocity.

Question 4

What is the equation for inertia?

Answer 4

Force/acceleration.

Question 5

When will the velocity of the object increase?

Answer 5

If the resultant force is in the same direction as the velocity. The acceleration is positive.

Question 6

When will the velocity of an object decrease?

Answer 6

If the resultant force is in the opposite direction to its velocity. The acceleration is negative.

Question 7

What is the weight?

Answer 7

Force acting on it due to gravity measured in Newton’s.

Question 8

What is mass?

Answer 8

The quantity of matter in it. Measured in kg.

Question 9

What is terminal velocity?

Answer 9

The object reaches a constant velocity when the frictional force on it is equal and opposite to its weight. The velocity is terminal. The resultant force is zero, so it’s acceleration is zero.

Question 10

What does the breaking force depend on?

Answer 10

The speed of the vehicle when the breaks are first applied.

The mass of the vehicle.

Question 11

What is the equation for stopping distance?

Answer 11

Stopping distance = thinking distance + braking distance.

Question 12

What factors affect stopping distances?

Answer 12

Tiredness, alcohol, drugs increase reaction times.
Speed.
Wet or icy roads.
Poor weather and road conditions increase stopping distance.
Poorly maintained vehicles.

Question 13

What is the equation for momentum?

Answer 13

Momentum of a moving object = mass x velocity.

Question 14

What is conservation of momentum?

Answer 14

In a closed system, the total momentum before an event is equal to the total momentum after the event.

Question 15

What happens when the impact time is longer?

Answer 15

The more the impact force is reduced.

Question 16

What happens if an object is elastic?

Answer 16

It returns to its original shape when the forces deforming it are removed.

Question 17

What is the extension of the strip of material or spring at any stage equal to?

Answer 17

Extension of the strip of material or spring at any stage = length at the stage - original length.

Question 18

What is Hooke’s law?

Answer 18

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

Question 19

What equation links force applied, spring constant and extension?

Answer 19

Force applied = spring constant x extension.

Question 20

What is spring constant?

Answer 20

The stiffer a spring is, the greater it’s spring constant.