(1) Classify the following as motion along a straight line, circular or oscillatory motion:
(i)Motion of your hands while running
(ii)Motion of a horse pulling a cart on a straight road
(iii) Motion of a child in a merry go – round.
(iv) Motion of a child in a seesaw.
(v) Motion of a hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
Ans
S.N.  Example of motion  Type of motion 
1.  Motion of your hands
while running 
Oscillatory 
2.  Motion of a horse pulling a cart on a straight road.  Straight line 
3.  Motion of a child in a merry go – round.

Oscillatory, Circular 
4.  Motion of a child in a seesaw.  Oscillatory 
5.  Motion of a hammer of an electric bell.  Oscillatory 
6.  Motion of a train on a straight bridge.  Straight line 
(2) Which of the following are not correct?
(i) The basic unit of time is second.
(ii) Every object moves with a constant speed.
(iii) Distances between two cities are measured in kilometers.
(iv) The time period of a given pendulum is not constant.
(v) The speed of a train is expressed in m/s.
Ans – The sentences which are not correct is given below:
(ii) Every object moves with a constant speed.
(iv)The time period of a given pendulum is not constant.
(v) The speed of a train is expressed in m/s.
(7) Show the shape of the distance – time graph for the motion in the following cases:
(i) A car moving with a constant speed.
(ii) A car parked on a side road.
Ans
(i) The shape of the distance – time graph for a car moving with a constant speed will always be straight line because car travel equal distance in equal interval of time. The graph is shown below:
(ii) The shape of the distance – time graph for a car parked on a road side will always be horizontal straight line parallel to time axis(x axis) because car is not travelling any distance with the increase of time. The graph is shown below:
(9) The basic unit of speed is;
(i) km/min
(ii) m/min
(iii)km/h
(iv)m/s
Ans
(i) km/min
(ii) m/min
(iii)km/h
(iv)m/s √
(10) A car moves with a speed of 40 km/h for 15min and then with a speed of 60km/h for the next 15 minutes. The total distance covered by the car is:
(i) 100km
(ii) 25km
(iii) 15km
(iv)10km
Ans
The speed of the car in first 15 min = 40km/h
Time taken by car = 15 min
= 15/60
= .25 hour
Distance travelled by car in first 15 min = Time × Speed
= .25 × 40
= 10.00km
The speed of the car in second 15 min = 60km/h
Distance travelled by car in second 15 min = Time × Speed
= .25 × 60
= 15.00km
Total distance = 10 +15
= 25km
(12) Figures given below shows the distance – time graph for the motion of two vehicles A and B. Which one of them is moving faster?
Ans
Draw a perpendicular CD on time axis to know the distance travelled by cars. It is clear from the figure that A travelled d_{A} distance which is more than distance d_{B} travelled by B.
(13) Which of the following distance – time graphs shows a truck moving with speed which is not constant?
(i)
(ii)
(iii)
(iv)
Ans–
(iii) is required answer because it shows non constant movement of truck.
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