# Physics Holiday Homework

Class IX

1. Is potential energy a vector or a scalar quantity?

2. A train travels at a speed of 60 km/hr for 0.52hr, at 30 km/h for the next 0.24hr and then at 70 km/h for the next 0.71h.What is the average speed of the train? 3. Plot the distance – time graphs

a) When the body is at rest

b) When the body is moving with a uniform speed

c) When the body is moving with a non-uniform speed.

4. The brakes applied to a car produced an acceleration of 6 ms-2 in the opposite direction of the motion. If the car takes 2s to stop after the application of brakes, calculate the distance it travels during this time. 5. What is positive acceleration and negative acceleration?

6. Why is the motion of Satellites around their planets considered an accelerated motion? 7. Study the time (t) versus distance (s) data given below and answer the questions that follow: Time (s)| Distance (m)|

0| 0|

2| 8|

4| 16|

6| 16|

8| 8|

10| 0|

8. A train is moving out of a railway station, is the platform at rest or in motion with respect to the train? 9. (a) Plot a graph of the following data with a proper choice of scale and interpret the type of motion represented by it. t (s)| 0| 2| 4| 6| 8| 10| 12|

d (m)| 0| 1| 4| 9| 16| 25| 36|

(b) Abdul, while driving to school compute the average speed for his trip to be 20 km/hr. On his return trip along the same route, there is less traffic and the average speed is 30 km/hr. What is the average speed of Abdul’s trip? 10. A moving train is brought to rest within 20 sec by applying brakes. Find the initial velocity, if the retardation due to brakes is 2 m/s2.

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