Mechanics

Question 1

What is a scalar with 2 examples

Answer 1

A magnitude of something, for example mass, energy

Question 2

What is a vector with 3 examples

Answer 2

A quantity with both magnitude and direction, for example, displacement, acceleration, velocity

Question 3

What is a moment

Answer 3

A turning effect of a force

Question 4

Moment =

Answer 4

force x perpendicular distance from the pivot to the line of action of the force

Question 5

What was does the principle of moments state

Answer 5

For a body to be in equilibrium, sum of clockwise moment about a point must equal sum of anticlockwise moment about that same point

Question 6

What is a couple

Answer 6

A pair of forces of equal magnitude, acting parallel to each other in opposite directions

Question 7

What is the mass of a body and what is it measured in

Answer 7

The amount of matter within a body; in kgs

Question 8

What is weight defined as

Answer 8

The force experienced by a mass due to a gravitational field strength

Question 9

Is weight a scalar or vector

Answer 9

A vector

Question 10

What is displacement

Answer 10

How far an abject has travelled from starting point in given direction

Question 11

Define velocity

Answer 11

Rate of change of an object’s displacement

Question 12

Acceleration =

Answer 12

Change is velocity / change in time

Question 13

What will acceleration look like on a D-T graph

Answer 13

A curve - upward sloping for acceleration, downward deceleration

Question 14

How to find velocity from a D-T graph

Answer 14

Work out the gradient, which is the velocity

Question 15

What does the gradient of a V-T graph show

Answer 15

Acceleration (as it =Δv/t)

Question 16

How to find displacement on a V-T graph

Answer 16

Area under the graph

Question 17

What is an object’s acceleration if it is free falling

Answer 17

Acceleration of g

Question 18

What is Newton’s first law of motion

Answer 18

A body will have constant velocity (and direction) unless an external resultant force acts upon it

Question 19

What does Newton’s second law state

Answer 19

Acceleration is proportional to force

Question 20

Force =

Answer 20

Mass x acceleration

Question 21

What does Newton’s third law state?

Answer 21

If object A exerts a forced on object B, then object B exerts an equal but opposite force back on A

Question 22

What are the two types of friction

Answer 22

Dry (between solids) and fluid (drag, fluid or air resistance)

Question 23

What does the effect of fluid friction depend on

Answer 23

Viscosity of the fluid and shape of the object

Question 24

What is lift

Answer 24

An upward force acting on an object in a fluid

Question 25

How does a car reach terminal speed

Answer 25

As car accelerates, the frictional forces acting against it increase. This reduces the resultant force on the car and reduces in acceleration. Eventually the car reaches a speed at which the frictional force is equal to the driving force; the car carries on at a constant speed

Question 26

Momentum =

Answer 26

Mass x velocity

Question 27

What is an elastic and inelastic collision

Answer 27

An elastic collision is where KE in conserved, whereas some is transferred to other forms in inelastic collisions

Question 28

What is always conserved when 2 objects collide, assuming no external forces act

Answer 28

The momentum of the 2 objects

Question 29

Define impulse

Answer 29

Force x time; the change in momentum

Question 30

Define work

Answer 30

The amount of energy transformed from one form to another when a force causes movement

Question 31

Give an example showing energy changes

Answer 31

Lifting up a box; gravity is the force opposed and GPE is the final energy form

Question 32

Work done =

Answer 32

Force x distance moved

Question 33

What is the area under a force/displacement graph

Answer 33

The work done

Question 34

Define power

Answer 34

The rate of work done; the amount of energy transferred from one form to another per second

Question 35

Power = (2)

Answer 35

change in work done / change in time | Force x velocity

Question 36

What does the conservation of energy state

Answer 36

Energy cannot be created or destroyed; total energy in = total energy out

Question 37

Efficiency =

Answer 37

useful output power / input power

Question 38

Work done against air resistance =

Answer 38

Loss in GPE - gain in KE

Question 39

For a falling object, what is loss in GPE equal to

Answer 39

Gain in its KE