Page 13 - Focus TG4 KSSM (Physics) Terbitan Penerbitan Pelangi Sdn Bhd

Physics Form 4 Chapter 2 Force and Motion I
(a) The graph in Figure 2.28(a) shows the Velocity-Time Graph
displacement of the tortoise from the 1. The gradient of the velocity-time graph gives
starting line from time t = 0 to 8 s, the value of the rate of change of velocity, that
(b) The graph in Figure 2.28(b) shows that is, the acceleration of the object.
throughout the time from t = 0 to 8 s, the
hare had a displacement of 0.5 m from the 2. The area under the graph gives the value of
starting point. Throughout the 8 seconds, the displacement of the object.
it did not move at all as it was sleeping. Table 2.2
3. The displacement-time graph of an object Graph of v against t Explanation
allows the displacement of the object at a (a)
specific time to be determined. v / m s –1
4. The gradient of the s-t graph of an object gives The object is not moving. Velocity Chapter
the rate of change of displacement, which is of the object is zero.
the velocity of the object.

Displacement, s / m Displacement, s / m 0 t /s 2
(b)
v / m s –1 The object is moving with uniform
Velocity = velocity.
Gradient of Acceleration = gradient of graph
–2
the s -t graph = 0 m s .
t /s
0
0 0 (c)
Time, t / s Time, t / s
v / m s –1 The velocity increases with
Figure 2.29 a uniform rate. The gradient
is positive and constant. The
5. Some common graphs are shown below. object is moving with uniform
Table 2.1 0 t /s acceleration.
Graph of s against t Explanation (d)
(a) v / m s –1 The velocity decreases with
s / m The displacement of the object
is always the same. Hence, a uniform rate. The gradient
the object is not moving or is negative and constant. The
stationary. object is moving with uniform
Velocity = gradient of graph deceleration.
= 0 m s -1
t /s t /s
0 0
(b)
s / m The displacement increases at
a uniform rate. The gradient 3. The area under the following graphs of v
of the graph is a constant. against t gives the displacement of the object
Hence, the object moves with respectively.
a uniform velocity.
(a) v / m s –1 (b) v / m s –1
t /s
0
(c)
s / m v v
The gradient of the graph is
increasing. The velocity of the
object is increasing. Hence,
the object moves with an 0 t /s 0 t /s
acceleration. t t
t /s (c)
0 v / m s –1
(d) s / m The gradient of the graph v
is decreasing. The velocity
of the object is decreasing. u
Hence, the object moves with 0 t /s
t /s a deceleration. t
0
29

02 FOC PHYSICS F4 3P.indd 29 29/01/2020 1:39 PM