8th Science Refresher course Topic 3 - Answer key

Lesson 3 - Force and Motion - Refresher course Answer

EVALUATION

1. Choose the correct answer 

1. The average speed of a car which travels 60 km in 3 hours 

(a ) 10 km / h 

(b ) 20 km / h

( c ) 30 km / h

(d ) 60 km / h

Answer : 

2. How the speed differs from velocity 

(a) speed is velocity in a given direction

(b) velocity is speed in a given direction

(c) They are the same

Answer : 

3. A car moves 80 km to the south, what is its displacement 

(a) 20km south

(b) 50km east

(c) 80km south

(d) 160km north

Answer : 

4. A particle moves in a circular path of radius “r“ ,what is the displacement of the particle 

after passing half of the circular path

(a) zero 

(b) r 

(c) 2r 

(d) r/2

Answer : 

5.Acceleration is the measure of the change in ----------

(a) density

 (b) motion

(c) velocity 

(d) mass

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II. Fill in the blanks

1. Minimum distance between the two places in straight line path ----------

Answer : 

2. The rate of change of velocity ---------------- .

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3. It he velocity of a particle increases with respect to time, it gets ------------- acceleration.

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4. In Speed—Time graph, the slope line gives ---------. value.

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5. SI unit of velocity is --------------.

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6. The negative acceleration is called as ------------------.

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7. Speed is a ---------- quantity.

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8. Velocity has ----------- value and ---------- value .

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9. Distance is ------------ measurement.

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10. SI unit of acceleration is --------------- .

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III. Match the following 

1. Displacement-a = (v- u ) / t

2. Speed- Uniform velocity

3. Acceleration- Metre (m)

4. Velocity - Distance / Time

5. Speed of light in vaccum -Displacement / Time

Answer :