Question

Question 1
A train accelerates from 36 km/h to 54 km/h in 10 sec. 
(i) Acceleration 
(ii) The distance travelled by car.




Question 2
A body whose speed is constant
(a) Must be accelerated
(b) Might be accelerated
(c) Has a constant velocity
(d) Cannot be accelerated.



Question 3
A truck traveling at 54 km/h is slow down to 36 km/h in 10 sec. Find the retardation 

Answer 1

1) Initial velocity, u  = 36 km/h = 10 m/s
Final velocity, v = 54 km/h = 15 m/s
Time, t = 10 s

i)Acceleration = v-u/t = 15 - 10/10 = 5/10 = 0.5 m/s²

ii) Distance traveled,s
v² - u² = 2as
15² - 10² = 2 x 0.5 x s
225 - 100  = s
s = 125 m

2) b. Might be accelerated. This is because the speed is constant but we don't have any idea about velocity. The velocity may or may not be changing. So there might be acceleration.

3) Initial velocity = 54 km/h = 15 m/s
Final velocity = 36 km/h = 10 m/s
Time  = 10 sAcceleration = 10 - 15/2 = -0.5 m/s²

This means the truck is retarding. So the retardation is 0.5 m/s²

Hope This Helps You

Answer 2

2. might be accelerated
3.Acceleration is given by
a=Δv/Δt
So a=-.5 m/s2
Negative sign implies retardation 
1.
a) Acceleration is given by
a=ΔvΔt
So a=.2 m/s2 
b) Distance is given by
S=ut+12at2 So s=125m