Mechanics: Linear motion

Question 1

physical quantity

Answer 1

that which can be measured, calculated and expressed in numbers eg length, force, masse etc

Question 2

scalar quantity

Answer 2

a physical quantity (measured, calculated, expressed in numbers) which has magnitude only and no direction eg mass, length, density

Question 3

vector quantity

Answer 3

a physical quantity (measured, calculated, expressed in numbers) which has both magnitude and direction eg force, velocity, acceleration, displacement

Question 4

distance, s

Answer 4

the distance between two points is how far one point is from the other,
scalar, units m, instrument meter stick, trundle wheel, opisometer
formula: average speed x time travelling

Question 5

time, t

Answer 5

time is used to measure the duration of events, put them in sequence, or to measure the interval between them,
scalar, units s,

Question 6

speed, v

Answer 6

speed is distance travelled per unit time
scalar, unit ms^-1
formula: v = s|t

Question 7

displacement, s

Answer 7

straight line distance in a given direction, how far your finish is from start
vector, units m + direction

Question 8

velocity, v

Answer 8

rate of change of displacement with respect to time

vector, units ms^-1

Question 9

acceleration, a

Answer 9

rate of change of velocity with respect to time, acceleration can be + speeding up, - slowing down, changing direction, 0 no change in velocity
vector, units ms^-2
formula: a = (v-u) | t

Question 10

average speed

Answer 10

(u+v) | 2

total distance | total time

Question 11

linear accelerated motion

Answer 11

acceleration is constant

Question 12

derive v= u + at

Answer 12

a = (v-u) | t

Question 13

derive s = ut + 1/2 at^2

Answer 13

s = (u=v) t
2
v = u + at

Question 14

derive v^2 = u^2 +2as

Answer 14

v = u + at
s = ut + 1/2 at^2

Question 15

distance time graphs

Answer 15

slope = speed

Question 16

velocity time graphs

Answer 16

slope = acceleration

area under graph = distance travelled

Question 17

adding scalar quantities

Answer 17

only add/subtract quantities that have the same units

Question 18

adding parallel/co linear vectors

Answer 18

draw diagram
net resultant force
add or subtract
don’t forget direction

Question 19

adding perpendicular vectors

Answer 19

redraw vectors as triangle tip to tail
place theta on horizontal
Pythagoras
SohCahToa
when giving direction start with horizontal theta is touching

Question 20

resolving vectors

Answer 20

redraw tip to tail and theta touching horizontal
draw up unless told otherwise
shortcut:
Fx(horizontal) = __cos degrees Fy(vertical): __sin degrees