dynamics

Question 1

d=vt

Answer 1

distance (m)= speed (ms^-1) time (s)

Question 2

a=v-u/t

Answer 2

acceleration (ms^-2) = final speed (ms^-1) - initial speed (ms^1) / time (s)

Question 3

how do you determine distance from a v-t graph

Answer 3

calculate the area under the graph

Question 4

newton’s 1st law

Answer 4

an object at rest will remain at rest and an object in motion will remain in motion with a constant speed in a straight line unless acted on by an unbalanced force

Question 5

what is a balanced force

Answer 5

the forces acting on an object are equal in size but in opposite directions

Question 6

what happens when an unbalanced force acts on an object

Answer 6

it will accelerate

Question 7

F(un)=ma

Answer 7

unbalanced force (N) = mass (kg) acceleration (ms^-2)

Question 8

how do you increase acceleration (decrease/increase)

Answer 8

decrease mass OR increase unbalanced force

Question 9

what is mass

Answer 9

a measure of how much matter there is in a substance

Question 10

what is weight

Answer 10

the force due to gravity acting on a mass

Question 11

W=mg

Answer 11

weight (N) = mass (kg) gravitational field strength (N kg^-1)

Question 12

what is newton’s 3rd law

Answer 12

if object a exerts an action force on object b, object b will exert an equal and opposite reaction force on object a (every action has its equal and opposite reaction)

Question 13

what is terminal velocity

Answer 13

the constant vertical speed reached by a falling object when the forces acting on it are balanced

Question 14

define average speed

Answer 14

the total distance travelled divided by the total time taken

Question 15

define instantaneous speed

Answer 15

the speed of a moving object at any particular instant in time

Question 16

describe an experiment to measure instantaneous speed

Answer 16

measure the length of a mask on a trolley, then put some textbooks under a ramp to create a slope. line up the light gate and connect it to the timer. the light gate will measure the time it took the mask to pass and then use v=dt to work out the speed

Question 17

define acceleration

Answer 17

the change in speed of a moving object per second

Question 18

what does an upwards slope represent on a v-t graph

Answer 18

acceleration

Question 19

what does a horizontal line represent on a v-t graph

Answer 19

constant speed

Question 20

what does a downwards slope represent on a v-t graph

Answer 20

deceleration

Question 21

what is friction

Answer 21

a force that acts in the opposite direction to an objects movement, created by two surfaces rubbing against each other

Question 22

how can friction be decreased

Answer 22

streamlining the object, decreasing surface area, lubricating surfaces (eg oiling), smoothing surfaces

Question 23

what would happen to the acceleration of the trolley if the forces remained the same but the mass was doubled

Answer 23

it would half

Question 24

an astronauts connecting rope snaps and she begins to drift away from her craft. why should she throw her spanner away from the craft?

Answer 24

the reaction force will push her back

Question 25

what forces are acting on a a falling object as it starts falling

Answer 25

weight

Question 26

as the speed of a falling object increases, what other force will also increase

Answer 26

air resistance

Question 27

what will eventually happen to the forces and speed of a falling object? (not air resistance)

Answer 27

the forces will balance out and it will go at a constant speed

Question 28

what is free fall

Answer 28

if an object is falling with no air resistance, it will continue accelerate downwards as there is nothing to balance out the force