44 UG008982 � Specification � Edexcel GCSE in Science: Single, Double, Separate Sciences B �

use the following units

� second (s), metre (m), metre per second (m/s), metre per second2 (m/s2), kilogram (kg), joule (J), newton (N), newton per kilogram (N/kg), watt (W), becquerel (Bq) (11.01)

interpret distance-time graphs including determination of speed from the gradient of a graph (11.02)

recall that velocity is speed in a stated direction (11.03)

recall and use the equation

� acceleration (m/s2) = change in velocity (m/s) ・time taken (s)

u v a - = (11.04)

interpret speed/time graphs

� determine the distance travelled from the area between the curve and the time axis

understand that the stopping distance of a vehicle is made up of

understand the factors affecting the stopping distance of a vehicle, including

recall a brief history of our understanding of forces and how they affect motion in a straight line including

� Galileo and Newton � balanced forces allow an object to continue in uniform motion in a straight line or to remain at rest

understand that when object A pulls or pushes object B then object B pulls or pushes object

understand that falling objects are acted on by a downward force (weight) and an upward force (air resistance) and that at the start of the fall the forces are unbalanced and the object accelerates (11.10)

understand that, when an object falls through the atmosphere, air resistance increases with increasing speed until it is equal in size to the weight of the falling object, when terminal speed (velocity) is reached (11.11)

understand that in the absence of air, all falling bodies accelerate at the same rate (11.12)

describe the forces acting on a car moving in a straight line on a horizontal surface

in the above example, understand how the balance of forces differs when the car is

understand that when an unbalanced force acts on an object, the acceleration depends on

recall and use the equation

� force (N) = mass (kg) ﾗ acceleration (m/s2)

� F = m ﾗ a (11.16)

recall and use the equation

� work done (J) = force (N) ﾗ distance moved in the direction of the force (m)

W = F ﾗ d (11.17)

understand that gravitational potential energy is stored positional energy, eg a swimmer on a diving board, a person lifting weights (11.18)

・recall and use the equation

� gravitational potential energy (J) =

mass (kg) ﾗ gravitational field strength (N/kg) ﾗ vertical height (m)

GPE = m ﾗ g ﾗ h (11.19)

recognise the equivalence of work done and energy transfer and recall that energy transferred (J) = work done (J) (11.20)

understand that power is the rate of doing work and is measured in watts (joules per second) (11.21)

recall that kinetic energy is movement energy (11.22)

recall and use the equation

� kinetic energy (J) = � ﾗ mass (kg) ﾗ velocity2 (m/s)2

KE = � ﾗ m ﾗ v2 (11.23)

recall that seismic waves are caused by earthquakes or �underground explosions� (11.24)

understand that longitudinal and transverse waves are transmitted through the Earth and that their paths and times of travel give information about the layered structure of the Earth: crust, mantle, outer (liquid) core and inner core (11.25)

recall that the Earth�s outermost layer, the lithosphere, is composed of plates in relative motion and that plate tectonic processes result in the formation, deformation and recycling of rocks (11.26)

understand that at plate boundaries, plates may

understand that the activity of a radioactive isotope decreases over a period of time and is measured in becquerels (11.28)

recall that the half-life of a radioactive isotope is the time taken for half the undecayed nuclei to decay, and the consequent problems arising in the disposal of radioactive waste (11.29)

use the concept of half-life to carry out simple calculations on the decay of a radioactive isotope (11.30)

describe the uses of radioactivity in the radioactive dating of archaeological specimens and rocks (11.31)