CLASS 7 || SUBJECT - SCIENCE || Chapter 13 || Motion and Time ||

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Chapter 13

Motion and Time

1.  A simple pendulum takes 32s to complete 20 oscillations, what is the time period of the pendulum?
Ans. Time taken to complete 20 oscillations = 32 s
Time taken to complete 1 oscillation = 32/20 s = 1.6 s
Time period of a pendulum is time taken by it to complete 1 oscillation.
Time period of pendulum is 1.6 seconds.

 

2.  The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Ans.Distance = 240 km
Time taken = 4 hours
Speed =Distance covered/time taken = 240km/4 hammer
=60 km/h
Speed of train =60 km/h

 

3.  The odometer of a car reads 57321.0 km when the clock shows the time 08:30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also.
Ans. Distance = 57336.0 km – 57321 km =15 km
Speed in km/min =15km/20 min = 3/4 km/min

Speed in km/hr =15 km/1/3 hr
=(15 x 3) km/hr
=45 km/hr.

4.  Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/min, calculate the distance between her house and the school.
Ans.Time taken =15 min
Speed = 2 m/min .
Distance = speed x time = 2 x 15 = 30 m
Distance between Salma’s school and her house is 30 m.

5.  NCERT Solutions Class 7 Science Chapter 13 Motion and Time Q7Show 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.

 

 

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