our dynamic universe

Question 1

law of the conservation of energy

Answer 1

energy cannot be created or destroyed, just changed from one form to another

Question 2

energy is the same as…

Answer 2

work done

Question 3

constant speed in a lift

Answer 3

forces are balanced and tension=weight

Question 4

up and accelerating or down and decelerating

Answer 4

forces are unbalanced and tension>weight

Question 5

up and decelerating or down and accelerating

Answer 5

forces are unbalanced and tension<weight

Question 6

momentum units

Answer 6

kgm/s

Question 7

law of the conservation of momentum

Answer 7

the total momentum before is equal to the total momentum afterwards in the absence of external forces

Question 8

momentum calculation

Answer 8

m1u1+m2u2 = m1v1+m2v2

Question 9

momentum in explosions

Answer 9

must still be conserved, the total momentum before is 0 therefor the total momentum after must be 0

Question 10

energy in collisions

Answer 10

total energy must always be conserved

Question 11

kinetic energy in collisions

Answer 11

kinetic energy is only conserved in elastic collisions

Question 12

energy: scalar or vector

Answer 12

scalar

Question 13

random uncertainty

Answer 13

random fluctuations can effect measurements from reading to reading

Question 14

systematic uncertainty

Answer 14

when the measurements are all affected in the same way, giving slightly incorrect values

Question 15

scale reading uncertainty

Answer 15

indicates how well a scale can be read, for widely spaced scales, this can be a little pessimistic

Question 16

random uncertainty calculation

Answer 16

max reading - min reading (all divided by) number of readings

Question 17

analogue scale reading uncertainty calculation

Answer 17

+/- half of the least division of the scale

Question 18

digital scale reading uncertainty calculation

Answer 18

+/- 1 in the least significant digit displayed

Question 19

how to compare uncertainties

Answer 19

take the percentage of each

Question 20

impulse calculation

Answer 20

Ft = mv-mu

Question 21

impulse: scalar or vector

Answer 21

vector

Question 22

impulse

Answer 22

the change in momentum

Question 23

impulse units

Answer 23

kgm/s

Question 24

momentum equation

Answer 24

p=mv

Question 25

inelastic collisions

Answer 25

kinetic energy is not conserved

Question 26

elastic collisions

Answer 26

kinetic energy is conserved (rare and only found in particles as sound and heat is usually let off)

Question 27

impulse graphs

Answer 27

the area under a force time graph is equal to the impulse

Question 28

how do crumple zones on cars protect passengers

Answer 28

the change in momentum can’t be changed at the time of the accident however crumpling on impact increases the time of collisions meaning the peak force is less causing less harm

Question 29

scalar

Answer 29

only magnitude

Question 30

vector

Answer 30

both magnitude and direction

Question 31

freely under gravity

Answer 31

-9.8m/s/s due to gravity

Question 32

area under velocity time graph

Answer 32

displacement

Question 33

the direction of acceleration

Answer 33

is the direction of the unbalanced force