P10 - Force and Motion

Question 1

How the acceleration of an object depends on the size of the resultant force acting upon it

Answer 1

The greater an object’s resultant force, the greater the object’s acceleration.

Question 2

Effect of an object’s mass on its acceleration

Answer 2

The greater an object’s mass, the smaller its acceleration for a given force.

Question 3

How to calculate an object’s resultant force with acceleration and mass

Answer 3

resultant force (N) = mass (kg) x acceleration (m/s^2)

F = ma

Question 4

Newton’s second law of motion

Answer 4

Object’s acceleration is directly proportional to the object’s resultant force ( F = ma )

Object’s acceleration is inversely proportional to object’s mass

Question 5

What is meant by the inertia of an object?

Answer 5

Its tendency to stay at rest or in uniform motion

Question 6

What is the inertial mass of an object?

Answer 6

A measure of the difficulty of changing an object’s velocity

Question 7

Intertial mass can be defined as …

Answer 7

Force / acceleration

Question 8

Difference between mass and weight

Answer 8

Object’s weight is the force acting on the object because of gravity,
Object’s mass is the quantity of matter in it.

Question 9

An object acted on only by gravity accelerates at …

Answer 9

about 10 m/s^2

Question 10

Terminal Velocity

Answer 10

The velocity an object eventually reaches when falling. The weight is then equal to the frictional force on the object.

Question 11

The resultant force acting on an object that’s falling at terminal velocity

Answer 11

When an object’s moving at terminal velocity, the resultant force is zero.

Question 12

Formula for weight

Answer 12

Weight (N) = mass (kg) x gravitational field strength (N/kg)

Gravitational field strength is essentially acceleration to a specific point.

Question 13

[Terminal Velocity] The objects reaches constant velocity when …

Answer 13

The frictional force on it is equal and opposite to weight.

This velocity is called its terminal velocity.

Question 14

The forces that oppose the driving force of a vehicle

Answer 14

Friction and air resistance.

Question 15

What does the stopping distance of a vehicle depends on

Answer 15

On the thinking distance and the braking distance

Question 16

Factors affecting stopping distance of a vehicle

Answer 16

High speed, poor weather conditions, poor vehicle maintenance affect braking distance

Poor reaction time AND high speed affect thinking distance.

High speed is the only factor that affects both braking and thinking distance.

Question 17

How to estimate the braking force of a vehicle

Answer 17

Force (N) = mass (kg) x acceleration (m/s^2)

This gives the braking force of a vehicle

Question 18

Thinking distance

Answer 18

The distance travelled by the vehicle in the time it takes the driver to react.

Question 19

Braking distance

Answer 19

The distance travelled by the vehicle during the time the brakes are applied / the braking force acts.

Question 20

How to calculate momentum

Answer 20

Momentum (kgm/s) = mass (kg) x velocity (m/s)

Momentum has both a size and a direction so it is a vector quantity.

Question 21

The unit of momentum

Answer 21

kg m/s

Question 22

What is a closed system? [aka Conservation of Momentum]

Answer 22

A system where the total momentum before an event is the same as the total after the event and no resultant force acts on any part of the system.

Question 23

Two objects that push each other apart move ___ with ___ and ___ ___

Answer 23

Away with EQUAL and OPPOSITE MOMENTUM

Question 24

What is meant when an object is called elastic?

Answer 24

If it returns to its original shape after removing the force deforming it.

Question 25

How to measure the extension of an object when it is stretched

Answer 25

The difference between the length of the object and its original length.

Question 26

How does a spring’s extension changes with the force applied to it?

Answer 26

Spring extension is directly proportional to the force applied, so long as the limit of proportionality is not exceeded. This relationship is linear.

Question 27

What is meant by the limit of proportionality of a spring?

Answer 27

Beyond the limit, spring extension is no longer proportional to the applied force. This relationship becomes non-linear.

Question 28

Hooke’s Law

Answer 28

Force applied (N) = spring constant (N/m) x extension (m)

Question 29

Where else does Hooke’s law apply to an object?

Answer 29

When the object is compressed.