Always show the details of your solution.
(a) The speed of light is 3.0x108
m/s. Express this speed in mm/ps.
(1 ps = 10-12
m/s = 3x108
m / s x [
10-12 s /1ps ] x [103 mm / 1 m ]
= 3x108 x 10-12 x 103
= 0.3 mm/ps
(b) It takes 4 hours to drain a container of 1000 m3 of water. What is the “mass flow rate”, in kg/s, of water from the container? (density of water =103 kg/m3)
Mass flow rate = volume flow rate x density
= [1000 m3/ 4h ]
x [103 kg/m3] x [1h / 3600 s]
= 69.4 kg/s
ball is thrown directly upward with an initial speed of 20.0 m/s from a height of 120 m above the ground.
Choose y to be positive upwards.
Write down the values with the correct sign for vo , a
= 20 m/s ; a = -
9.8 m/s2 ;
= 120 m
(i) At maximum height, what is the
velocity of the ball?
v = 0
At maximum height, what is the acceleration due to gravity? (Give the correct
= - 9.8 m/s2
What is the speed of the ball just before it hits the ground?
v2 = vo2 + 2 a ( y – yo)
= (20)2 + 2 ( -9.8)( 0 – 120)
= 400+2352 =
v = ±
Speed = 52.5 m/s