ncert Science book answers with explanation for class 7 ch-13 Q5
Answers
Explanation:
Answers of NCERT Solutions for Class 7 Science Chapter 13 Motion and Time
Exercise Questions
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 on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
Solution:
i) oscillatory
ii) Motion along a straight line
iii) Circular motion
iv) Oscillatory motion
v) Oscillatory motion
vi) Motion along a 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 kilometres.
(iv) The time period of a given pendulum is constant.
(v) The speed of a train is expressed in m/h.
Solution:
Incorrect statements are:
(ii) Every object moves with a constant speed.
(iv) The time period of a given pendulum is constant.
(v) The speed of a train is expressed in m/h.
3. A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?
Solution:
Number of oscillations = 20
Total time taken to complete 20 oscillations = 32 s
time period calculation
4. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Solution:
Distance between two stations = 240 kms
Total time take = 4 hrs/240 minutes
Speed calculation
= 60 km/h
5. 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.
Solution:
Initial reading of the odometer = 57321.0
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