Page 42 - text book form physics kssm 2020

Example 2
As a sports car moves along Solution:
1
a straight track, its velocity Initial velocity, u = 40 m s –1 s = (u + v)t
–1
is 40 m s . After 3 seconds, Final velocity, v = 50 m s –1 2
1
the sports car has reached Time, t = 3 s = (40 + 50)(3)
–1
50 m s . Calculate Displacement, s = ? 2
its displacement. = 135 m

Example 3

An athlete starts his run Solution:
from rest and achieves a 1 2
maximum velocity after Initial velocity, u = 0 m s –1 s = ut + at
2
accelerating uniformly for Time, t = 8.0 s 1 2
8.0 s. If the displacement Displacement, s = 40 m 40 = (0)(8) + (a)(8 )
2
of the athlete is 40 m, Acceleration, a = ? 40 = 0 + 64a
determine his acceleration. 2
2 × 40
a =
64
= 1.25 m s –2

Example 4
Maria rides a bicycle at a Solution:
–1
velocity of 8 m s . She –1 2 2
brakes suddenly and stops Initial velocity, u = 8 m s v = u + 2as
–1
2
2
after a distance of 2 m. Final velocity, v = 0 m s 0 = 8 + 2(a)(2)
What is the acceleration of Displacement, s = 2 m –4a = 64 –2
Maria and her bicycle? Acceleration, a = ? a = –16 m s
–2
Negative value shows that Maria accelerates at 16 m s in the
opposite direction to the motion of the bicycle.

2.1
Formative Practice 2.1

1. Explain the difference between
(a) distance and displacement (b) speed and velocity

2. A car moving along a straight road at a velocity of 30 m s reduces its velocity at a
–1
constant rate until it stops after 5 s. What is the acceleration of the car?
3. Aina rides a smart personal transporter at the Perdana Botanical Gardens. The transporter
–1
accelerates uniformly from a velocity of 1 m s to a velocity of 5 m s in 0.5 minutes.
–1
Calculate the displacement of the transporter.
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36 2.1.3
2.1.3