1. Motion, forces and energy (1-8)

Question 1

how to measure a variety of time intervals

Answer 1

analogue clock

digital timer

Question 2

Determine an average value for a small distance and for a short interval of time by measuring multiples (including the period of oscillation of a pendulum)

Answer 2

(use stop-watch to) time oscillations

(use of fiduciary) aid to determine a complete cycle

(use of) multiple oscillations AND division (to determine period)

Question 3

Describe scalar and vector quantities with examples

Answer 3

a scalar quantity has magnitude (size) only and a vector quantity has magnitude and direction-

distance, speed, time, mass, energy and temperature

force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength

Question 4

Define speed and velocity

Answer 4

distance travelled per unit time; v = s/t

speed in a given direction

Question 5

Define acceleration

Answer 5

change in velocity per unit time; a=∆v/ ∆t

Question 6

distance–time graph

Answer 6

(a) at rest
(b) moving with constant speed
(c) accelerating
(d) decelerating

Question 7

speed–time graph

Answer 7

(a) constant acceleration
(b) increasing acceleration
(c) decreasing acceleration

Question 8

using speed-time and distance-time to determine

Answer 8

speed from the gradient of a straight line section of a distance–time graph

area under a speed–time graph to determine the distance

acceleration from the gradient of a speed–time graph

Question 9

acceleration of free fall

Answer 9

acceleration of free fall g for an object near to the surface of the Earth is approximately constant and is approximately 9.8m/s2

Question 10

Describe the motion of objects falling in a uniform gravitational field with and without air/ liquid resistance (including reference to terminal velocity)

Answer 10

(initially there is acceleration due to) weight OR gravitational force OR unbalanced force / resultant force / downward force

(then) air resistance increases as speed or velocity increases

(as air resistance increases) resultant force downwards decreases OR acceleration decreases

constant speed when air resistance = weight / gravitational force

Question 11

Define mass, weight and gravitational field strength, equation and how to compare

Answer 11

a measure of the quantity of matter in an object at rest relative to the
observer

weight is a gravitational force on an object that has mass

gravitational field strength as force per unit mass;
g = W/m this is equivalent to the acceleration of free fall

weights (and masses) may be
compared using a balance

Question 12

density

Answer 12

density as mass per unit volume; ρ = m/V

density of a liquid,

regularly shaped solid

irregularly shaped solid which sinks in a liquid
(volume by displacement)- place it in a measuring cylinder containing water and calculate the change in volume

Question 13

forces may produce changes in

Answer 13

size and shape of an object

Question 14

Define spring constant, limit of proportionality and extension

Answer 14

Define the spring constant as force per unit extension; k = F/x

limit of proportionality- up to this limit, the extension on a load is proportional to load. this is Hooke’s law.

extension- increased length of an object when load is attached to it

curves and slopes up less steeply, not proportional it is permanently damaged and deformed so won’t return t its original position once the load is removed.

Question 15

force eqn

Answer 15

F = ma and the force and the acceleration are in the same direction

Question 16

resultant force and object’s motion

Answer 16

an object either remains at rest or continues in a straight line at constant speed unless acted on by a resultant force

a resultant force may change the velocity of an object by changing its direction of motion or its speed

Question 17

Describe, qualitatively, motion in a circular path due to a force perpendicular to the motion

Answer 17

(a) speed increases if force increases, with mass and radius constant

(b) radius decreases if force increases, with mass and speed constant

(c) an increased mass requires an increased force to keep speed and radius constant

Question 18

Describe friction in solid, liquid and gas

Answer 18

force between two surfaces that may impede motion and produce heating ( slows the object down and causes an increase in thermal energy)

friction (drag) acts on an object moving through a liquid

friction (drag) acts on an object moving through a gas (e.g. air resistance)

Question 19

Describe moment

Answer 19

Describe the moment of a force as a measure of its turning effect and examples- tap, door handle, scissors

moment = force × perpendicular distance from the pivot

Question 20

principle of moment

Answer 20

if an object is balanced, the total clockwise moment about pivot equals the total anti-clockwise moment

Question 21

Equilibrium conditions

Answer 21

when there is no resultant force and no resultant moment, an object is in equilibrium

Question 22

Describe an experiment to determine the position of the centre of gravity—-

Question 23

State what is meant by centre of gravity

Describe, qualitatively, the effect of the position of the centre of gravity on the stability of simple objects

Answer 23

the point at which the object’s weight may be considered to act/ concentrates.

if the centre of gravity is lower and base is wider, the object is more stable

Question 24

Define momentum, impulse, resultant force

Answer 24

momentum as mass × velocity; p = mv

impulse as force × time for which force
acts; impulse = F∆t = ∆(mv)

resultant force as the change in momentum per unit time;
F = ∆p/∆t

Question 25

state the principle of conservation of momentum

Answer 25

the total momentum is constant and does not change because of an interaction between bodies such as collisions

whenever two objects interact, the total amount of momentum before they interact is the same as the total amount of momentum afterwards.

Question 26

energy may be stored as

Answer 26

kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal)

Question 27

Describe how energy is transferred between stores during events and processes

Answer 27

transfer by forces (mechanical work done), electrical currents (electrical work done), heating, and by electromagnetic, sound and
other waves

Question 28

principle of the conservation of energy

Answer 28

Energy cannot be created or destroyed, it can only be stored or transferred. total amount of energy before and after transfer is constant.

Question 29

What is equal to energy transferred

Answer 29

mechanical or electrical work done.

W = Fd = ∆E

Question 30

Define efficiency

Answer 30

(%) efficiency = (useful energy output)/ (total energy input) (× 100%)

(%) efficiency = (useful power output)/(total power input) (× 100%)

Question 31

radiation from the Sun is the main source of energy for all our energy resources except and how is energy from sun released

Answer 31

geothermal, nuclear and tidal

energy is released by nuclear fusion in the Sun

Question 32

Describe how useful energy may be obtained, or electrical power generated, from—

Answer 32

(a) chemical energy stored in fossil fuels

(b) chemical energy stored in biofuels

(c) water, including the energy stored in waves, in tides, and in water behind hydroelectric dams

(d) geothermal resources

(e) nuclear fuel

(f) light from the Sun to generate electrical power (solar cells)

(g) infrared and other electromagnetic waves from the Sun to heat water (solar panels) and be the source of wind energy

Question 33

Describe advantages and disadvantages of each method in terms of renewability, availability, reliability, scale and environmental impact—-

Question 34

Define power

Answer 34

work done per unit time and also energy transferred per unit time;

P = W/t
P = ∆E/t

Question 35

Define pressure

Answer 35

force per unit area. p = F/A

weight from heeled shoes is spread over a smaller area which exerts a higher pressure.

Question 36

how the pressure beneath the surface of a liquid changes with depth and density of the liquid

Answer 36

∆p = ρg∆h gravity is constant so more depth and more density= more pressure