21.  Rohit completes a semi circular path of radius R in 10 seconds. Calculate average speed and average velocity in m/s.

A. \(\frac{2\pi R}{10},\frac{2R}{10}\)

B. \(\frac{\pi R}{10},\frac{R}{10}\)

C. \(\frac{\pi R}{10},\frac{2R}{10}\)

D. \(\frac{2\pi R}{10},\frac{R}{10}\)

Answer : Option C

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22.  A particle moves 4m in the south direction. Then it moves 3m in the west direction. The time taken by the particle is 2 second. What is the ratio between average speed and average velocity ?

A. \(\frac{5}{7}\)

B. \(\frac{7}{5}\)

C. \(\frac{14}{5}\)

D. \(\frac{5}{14}\)

Answer : Option B

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23.  A particle is projected vertically upwards with velocity 30 m/s. Find the ratio of average speed and instantaneous velocity after 6 s. \(\left [ g=10\ ms^{-2} \right ]\)

A. \(\frac{1}{2}\)

B. 2

C. 3

D. 4

Answer : Option A

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24.  The motion of a particle along a straight line is described by the function \(x=\left ( 3t-2 \right )^{2}\). Calculate the acceleration after 10s.

A. \(9\ ms^{-2}\)

B. \(18\ ms^{-2}\)

C. \(36\ ms^{-2}\)

D. \(6\ ms^{-2}\)

Answer : Option B

Explanation :

\(v=\frac{\mathrm{d} x}{\mathrm{d} t}\) and \(a=\frac{\mathrm{d} v}{\mathrm{d} t}\)

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25.  

Given figure shows a graph at acceleration \(\rightarrow \) time for a rectilinear motion. Find averageacceleration in first 10 seconds.

A. \(10\ ms^{-2}\)

B. \(15\ ms^{-2}\)

C. \(7.5\ ms^{-2}\)

D. \(30\ ms^{-2}\)

Answer : Option C

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26.  A body starts its motion with zero velocity and its acceleration is \(3\ ms^{-2}\). Find the distance traveled by it in fifth second.

A. 15.5 m

B. 17.5 m

C. 13.5 m

D. 14.5 m

Answer : Option C

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27.  A body is moving in x direction with constant acceleration \(\alpha \). Find the difference of the displacement covered by it in nth second and \((n-1)^{th}\) second.

A. \(\alpha \)

B. \(\frac{\alpha }{2}\)

C. \(3\alpha \)

D. \(\frac{3\alpha }{2}\)

Answer : Option A

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28.  What does the speedometer measure kept in motorbike ?

A. Average velocity

B. Average speed

C. Instantaneous speed

D. Instantaneous velocity

Answer : Option C

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29.  The displacement of a particle in x direction is given by \(x=9-5t+4t^{2}\). Find the velocity at time \(t = 0\)

A. -8 m/s

B. -5 m/s

C. 3 m/s

D. 10 m/s

Answer : Option B

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30.  A freely falling particle covers a building of 45m height in one second. Find the height of the point from where the particle was released. \(\left [ g=10\ ms^{-2} \right ]\)

A. 120m

B. 125m

C. 25m

D. 80m

Answer : Option B

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