Mechanics (1&2)

Question 1

What do forces do to elastic objects?

Answer 1

The extension of an elastic object is directly proportional to the force applied.

Question 2

How does the extension of a spring vary with the applied force?

Answer 2

The extension of an elastic object is directly proportional to the force applied.

Question 3

How is work done calculated? What is the unit?

Answer 3

FxD. J/NM

Question 4

What is the meaning of power?

Answer 4

In physics, power is the rate of doing work. It is the amount of energy consumed per unit time.

Question 5

What factors affect the Gravitational Potential Energy of an object?

Answer 5

its mass and its height above the Earth’s surface. The weight of an object is the size of the force of gravity pulling the object down.

Question 6

How do you calculate the kinetic energy of a moving object?

Answer 6

1/2 x mv(squared)

Question 7

How is the velocity of an object different to its speed?

Answer 7

Velocity has direction.

Question 8

What is Newton’s 3rd law?

Answer 8

For every action, there is an equal and opposite reaction.

Question 9

What is the momentum of an object?

Answer 9

(MxV). All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion.

Question 10

What is the principle of conservation of momentum?

Answer 10

The principle of conservation of momentum states that when you have an isolated system with no external forces, the initial total momentum of objects before a collision equals the final total momentum of the objects after the collision

Question 11

When does the principle of conservation of momentum apply?

Answer 11

When working out the mass, velocity or momentum of an object in an explosion or collision.

Question 12

What is regenerative braking?

Answer 12

A method of braking in which energy is extracted from the parts braked, to be stored and reused.

Question 13

How are vehicles designed to provide safety to people during a crash?

Answer 13

Airbags, Crumple zones, Seatbelts, Increased side door strength, Strong occupant compartment (where people sit in the car), Head rests (prevent whiplash).

Question 14

What do forces do to an object’s motion?

Answer 14

When the forces acting on an object are balanced, the object is either at rest or moving with a constant velocity. Unbalanced forces can cause an object to accelerate or decelerate. Unbalanced forces can also cause an object to change direction.

Question 15

How is a resultant force worked out?

Answer 15

An object may have several different forces acting on it, which can have different strengths and directions. They can be added together to give the resultant force.

Question 16

How are mass, force and acceleration related?

Answer 16

They are directly proportional. If you increase the force applied to an object, the acceleration of that object increases by the same factor. In short, F=MxA

Question 17

What is acceleration?

Answer 17

The rate of change of velocity per unit of time.

Question 18

What is the unit for acceleration?

Answer 18

M/S

Question 19

What info can we get from a distance-time graph?

Answer 19

Background information:
The vertical axis of a distance-time graph is the distance travelled from the start, and the horizontal axis is the time taken from the start.

Features of the graphs:
When an object is stationary, the line on the graph is horizontal. When an object is moving at a steady speed, the line on the graph is straight, but sloped.
The diagram shows some typical lines on a distance-time graph.

Question 20

How do we work out the gradient of a straight line?

Answer 20

To find the gradient of a straight line:
1.) Choose any two points on the line.
draw a right-angled triangle with the line as hypotenuse.
2.) Use the scale on each axis to find the triangle’s: vertical length.
3.) horizontal length.
4.) work out the vertical length ÷ horizontal length.
5.) the result is the gradient of the line.

Question 21

What information can we get from a velocity-time graph?

Answer 21

Velocity-time graph reveals useful information about the acceleration of the object. If the acceleration is zero, then the slope is zero

Question 22

What differences are there between the mass and weight?

Answer 22

Mass is the actual amount of material contained in something and is measured in kg, gm, etc. Whereas weight is the force exerted by the gravity on that object mg.

Question 23

How can the maximum terminal velocity of a vehicle be increased?

Answer 23

When the upwards force (air resistance) and downwards force (weight) equal each other. At this point the object travels at its fastest speed.

Question 24

What is the stopping distance of a vehicle?

Answer 24

Stopping distance = thinking distance + braking distance