All numerical problem of chapter 1 (motion)
Answers
Answer:
Question 1
A train accelerates from 36 km/h to 54 km/h in 10 sec.
(i) Acceleration
(ii) The distance travelled by car.
Answera. Acceleration is given by
a
=
Δ
v
Δ
t
Δ
v
=
54
−
36
=
18
k
m
/
h
r
=
18
×
1000
3600
m
/
s
=
5
m
/
s
So a=.5 m/s2
b. Distance is given by
S
=
u
t
+
1
2
a
t
2
Now u=36 km/hr =10m/s
s
=
10
×
10
+
1
2
×
.5
×
10
2
So s=125m
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.
Answermight be accelerated
Question 3
A truck travelling at 54 km/h is slow down to 36 km/h in 10 sec. Find the retardation
AnswerHere u=54 km/h =15 m/s ,v=36 km/h=10 m/s
Acceleration is given by
a
=
Δ
v
Δ
t
a
=
10
−
15
10
=
−
.5
So a=-.5 m/s2
Negative sign implies retardation
Question 4
A particle is moving in a circle of diameter 20 m. What is its distance and as per the table given below
Rounds Displacement Distance
1
1.5
2
2.5 AnswerAfter every round, particle comes to it starting position. So displacement at full rounds will be zero
Rounds Displacement Distance
1 0
20
π
1.5 20 m
30
π
2 0
40
π
2.5 20m
50
π
Question 5
A scooter travelling at 10 m/s speed up to 20 m/s in 4 sec. Find the acceleration of scooter.
Answer