Mechanics

Question 1

v =

Answer 1

d/t

Question 2

d =

Answer 2

v x t

Question 3

t =

Answer 3

d/v

Question 4

Distance-Time Graphs

Answer 4

• If the graph is a straight line then this shows that the object is moving at a constant speed
• Steeper the line, the faster the object is moving
• Horizontal the object is not moving (stationary)
• Gradient = rise/run
• Curved line the object is changing speed with accelerating or decelerating

Question 5

Speed-Time Graphs

Answer 5

• A positive gradient shows the object is accelerating
• A negative gradient shows the object is decelerating
• If the line is horizontal the object is moving at a constant speed
• Gradient = rise/run = acceleration
• Distance = area of triangle = bxh/2

Question 6

Mass (m)

Answer 6

The amount of matter in an object. It is in kilograms (kg). It does nor change when the object changes its position.

Question 7

Weight (W)

Answer 7

The force of gravity acting on an object. It is measured in newtons (N). It may change if an object changes its position.

Question 8

Support Force

Answer 8

When an object pushes down on a surface, the surface pushes back on the object. It always 90 degrees to the surface of the object is on.

Question 9

Thrust Force

Answer 9

A push force, e.g from an engine.

Question 10

Friction Force

Answer 10

A force that is always in the opposite direction to any motion.

Question 11

Buoyancy Force

Answer 11

An upwards force from a fluid e.g water or air.

Question 12

Lift Force

Answer 12

The upwards push on a wing (e.g an aircraft) due to its motion through air.

Question 13

Tension Force

Answer 13

A pulling force e.g due to a rope or chain.

Question 14

Weight Force

Answer 14

Due to gravity and it always acts straight down.

Question 15

Weight =

Answer 15

mass x strength of gravity = mg

Question 16

What is the strength of gravity on earth?

Answer 16

10 Nkg-1

Question 17

Gravitational Fields

Answer 17

All objects are surrounded by force field. This field can be drawn as a series of lines with arrows;

• the direction of the gravity force (weight) that would act on a mass placed at that point
• the relative strength of the gravitational field - the close the field lines, the stronger the field.

Question 18

Names of Gravitational Fields on Earth

Answer 18

Radial Field and Uniform Field
(earth from space) (surface of earth)

Question 19

Balanced Forces

Answer 19

Means the object is at a constant speed

Question 20

Unbalanced Forces

Answer 20

Means the object is accelerating/decelerating

Question 21

When two arrows are the same direction

Answer 21

Total force = both arrows added up N

Question 22

When two arrows are the opposite direction

Answer 22

Total force = difference between them

Question 23

When an arrow is going up/down and one is going left/right

Answer 23

Total force = to find the hypotheses of a triangle (a2 +b2 = c2)

Question 24

Newton’s Second Law

Answer 24

the net force on an object is proportional to the acceleration of the object;

F= ma

(if no given the force times the mass by 10)

Question 25

Newton’s Third Law

Answer 25

for every action on one object there is an equal but opposite reaction on another object

Question 26

Solid Friction

Answer 26

Is the force that opposes motion between the surfaces of two solid objects. The size of the solid friction;

-Depends on the smoothness of the two surfaces.

Question 27

Fluid Resistance

Answer 27

Is created when an object moves through a fluid (liquid or gas). It is also called drag. If fluid is air, then the term air resistance is used.The size of the fluid resitance depends on;

• the speed of the object relative to the fluid
• the size and shape of the object
• the fluid used (its viscosity)

Question 28

Terminal Velocity

Answer 28

The highest velocity attained by an object falling through a fluid. It is observed when the sum of drag force and buoyancy is equal to the downward gravity force acting on the object.

Question 29

Energy

Answer 29

The capacity to do work which means you need energy for things to happen.

Question 30

Kinetic Energy

Answer 30

Energy of a moving object (Ek)
e.g car, ball that is moving

Question 31

Gravitational Potential Energy

Answer 31

Energy of an object due to its height above the ground (Ep)
e.g building, desk

Question 32

Chemical Potential Energy

Answer 32

Energy stored in the chemical bonds of a substance
e.g batteries, petrol

Question 33

Elastic Potential Energy

Answer 33

Energy stored in a stretched or compressed object
e.g rubber band, slinky

Question 34

Sound Energy

Answer 34

e.g speaker, mouth

Question 35

Light Energy

Answer 35

e.g sun, lightbulb

Question 36

Heat Energy

Answer 36

e.f fire, sun

Question 37

Electrical Energy

Answer 37

e.g charges, phones

Question 38

Nuclear Energy

Answer 38

e.g bomb, nuclear power

Question 39

Conversation Of Energy

Answer 39

Energy cannot be created no destroyed but instead is just converted from on form to another

Question 40

Work

Answer 40

When a force moves an object for some distance in the direction of the force we say that work is done on the object by force. W = fd

The amount of energy gained or lost is equal to the amount of work done.

Question 41

Power

Answer 41

Power is the rate of doing work. The faster something can do work, the more powerful it is. P = W/t