P2 | motion and forces

Question 1

what is a scalar quantity?

Answer 1

magnitude but no direction

Question 2

what is a vector quantity?

Answer 2

magnitude and direction

Question 3

examples of scalar quantities

Answer 3

speed
distance
mass
temperature
density 
pressure
volume
work
power

Question 4

examples of vector quantities

Answer 4

velocity
momentum
displacement
weight
acceleration 
force

Question 5

what is velocity?

Answer 5

speed in a stated direction

Question 6

what does the area under a velocity-time graph represent?

Answer 6

distance

Question 7

average speed of walking

Answer 7

1.4 m/s

Question 8

average speed of running

Answer 8

3 m/s

Question 9

average speed of wind

Answer 9

5 to 20 m/s

Question 10

average speed of sound in air

Answer 10

340 m/s

Question 11

average speed of cycling

Answer 11

5.5 m/s

Question 12

average speed of cars

Answer 12

normal road = 13 m/s

motorway = 31 m/s

Question 13

what direction does centripetal force act on a circle?

Answer 13

towards the CENTRE of the circle

Question 14

why does an object moving in circular orbit have a constant speed but changing velocity?

Answer 14

• as object moves in a circular motion, it is constantly changing direction
• since velocity is a vector quantity (magnitude and direction), the velocity is changing because the direction is changing
• speed (magnitude) stays constant while direction changes

Question 15

what is inertial mass?

Answer 15

the measurement of how difficult it is to change the velocity of an object

Question 16

what is newton’s third law?

Answer 16

when two objects interact, the forces they’re exert on each other are equal and opposite

Question 17

momentum formula

Answer 17

mass (kg) x velocity (m/s)

Question 18

force formula

Answer 18

change in momentum (kg m/s) / time (s)

mass x acceleration