PREPWALK

1. Physics
INTRODUCTION TO MOTION
SHORT REVISION SERIES

2. Useful parameters
 Dispalcement: Distance traveled in a specific
direction
 Speed: Rate of change of distance with time
 Uniform speed: When the ratio of
distance/time is constant through out
journey.
 Velocity: rate of change of displacement with
time. v = s/t
 Acceleration: Rate of change of velocity
increase with time. a = v/t

3. Useful equations
 S = (v + u) x t .............1
2
Since a = v + u
t
• v + u = at
• v = u + at ..................2
• v2 = u2 + 2as .............3
• s = ut + ½ at2 ...........4

4. eg

5. Area under a velocity – time
graph
 Consider this question from UTME 1993
 The diagram above shows a velocity-time graph
representing the motion of a car. Find the total distance
covered during the acceleration and retardation periods of
the motion.
A. 75m B. 150m C. 300m D.375m
V
(m/s
t (s)
0
10 40 50
10 A C
B D E

6.  Distance travelled during retardation = Area
of CDE
 Distance travelled during acceleration = Area
of OAB
 Area of CDE = ½ (10 x 5) = 25
 Area of OAB = ½ (10 x 10) = 50
 Total = area of CDE + OAB = 25m + 50m =
75m.
 Answer is A.

7. Motion under gravity
 Remember when answering questions
involving vertical fall under the influence of
gravity use equations 1 to 4 highlighted
previously and substitute acceleration a for
+g if downwards fall or a = -g if going
upwards against gravity.

8. eg
 Consider this question from UTME 98
 In a free fall, a mass of 1kg drops from a
height of 125m from rest in 5s. How long will
it take another body of mass 2kg to fall from
rest from the same height?
A. 5s B. 10s C. 12s D. 15s
(g = 10ms-2)

9.  s = ut + ½ gt2
from rest u = 0
s = ½ gt2
t = √(2s/g)
Note that t is independent of mass, therefore
the mass does not matter.
So they will fall at the same time = 5s.

10. END