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Q1. Which of the following quantity remains constant during the uniform circular motion?

• Velocity
• Angular acceleration
• Angular velocity
• Speed

Solution

 When a body is in uniform circular motion, its speed remains constant but its velocity, angular acceleration, angular velocity changes due to change in its direction.

Q2. The velocity time graph will be a straight line with a non-zero slope for the motion of a ball which is launched vertically up and then comes back down under the influence of gravitational acceleration. Choose the correct option

•     True  
•     False
•     Can’t predict
•     none  

Solution

It is true.  

Q3. Rain falls at a speed of 50m/s and a child walks on a straight road from east to west at a speed of 100m/s. To find the direction in which the child should hold the umbrella use

• relative speed of child with respect to rain
• relative speed of rain with respect to child
• resultant speed of child and rain
• resultant speed of rain and child

Solution

Rain falls at a speed of 50m/s and a child walks on a straight road from east to west at a speed of 100m/s. To find the direction in which the child should hold the umbrella use relative speed of rain with respect to child.

Q4.  A coordinate system that enables us to describe the position of a body in space at any instant of time is called

• Origin
• Reference point
• Intersection point
• Reference frame

Solution

A frame of reference is a set of coordinate axes that helps to determine the position of a body in space at any instant of time.

Q5. A car moving with a speed of 50 km/h can be stopped by applying brakes after at least 10 m. What will the minimum stopping distance if the same car is moving at a speed of 100 km/h?

• 20.2 m
• 30 m
• 40. 1 m
• 25.4 m

Solution

Q6. If the path length covered by a body is zero then

• its displacement is zero.
• the displacement > 0.
• the displacement < 0.
• displacement may or may not be zero.

Solution

if the body has not moved at all from its initial position, i e the final position is same as that of initial position. then its displacement must be zero.

Q7. What does the slope of x-t graph represent?

• speed
• velocity
• distance
• displacement

Solution

 The slope of x-t graph represents velocity

Q8. Which of the following quantity remains constant during the uniform circular motion?

• Velocity
• Angular acceleration
• Angular velocity
• Speed

Solution

When a body is in uniform circular motion, its speed remains constant but its velocity, angular acceleration, angular velocity changes due to change in its direction.  

Q9. The ratio of displacement to distance is

• Less than 1
• Equal to 1
• Greater than 1
• Either less than or equal to 1

Solution

As the magnitude of displacement always either less than or equal to distance travel. Hence, the numerical ratio of displacement to distance is either less than or equal to 1.

Q10. A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. What will be its acceleration?

• a = –u²/8
• a = –u/8
• a = u²/8
• a = u/8

Solution

If u is the initial velocity, then v = u/2, S = 3 cm    

Q11. Two stones of different masses are thrown vertically upward with same initial velocity. Which one will rise to a greater height?

• Stone of lower mass
• Stone of higher mass
• Both will rise to the same height
• Information given is insufficient

Solution

Both the stones will rise to the same height. It is because, for a body moving with given initial velocity and acceleration, the distance covered is same. It does not depend on body's mass.

Q12. On velocity-time graph, a horizontal line indicates:

• zero displacement
• zero acceleration
• zero velocity
• constant acceleration

Solution

A horizontal line on a velocity - time graph indicates that object is moving with constant velocity..

Q13. A body is said to have uniform speed if it covers

• Equal distances in unequal time intervals
• Unequal distances in unequal time intervals
• Unequal distances in equal time intervals
• Equal distances in equal time intervals

Solution

A body has a uniform speed if it covers equal distances in equal intervals.

Q14. The position of a particle is given by x = at³  where a is  a constant. Find the velocity as a function of time.

• v = a.t⁴/4
• v = a.3/t²
• v = a.3t²
• v = 3t²

Solution

Velocity = dx/dt = a.3t² = 3at²

Q15. The area of acceleration time graph indicates:

• Acceleration
• Average Speed
• Velocity
• Displacement

Solution

 The area of acceleration-time graphs indicate the average speed.

Q16. A ball is thrown vertically upward. At the highest point in its path, which of the following statements is correct?

• The velocity and acceleration are both zero
• The velocity is zero and the acceleration is pointing down
• The acceleration is zero and the velocity is pointing down
• The acceleration is zero and the velocity is pointing up

Solution

The acceleration due to gravity is constant throughout the flight of the ball. It's magnitude is g=9.8 m/s², and it is the same at all points that the ball is not in contact with the ground or your hand. It is the velocity that is zero.

Q17. The motion of a freely falling body is an example of:

• uniformly accelerated motion
• non uniformly accelerated motion
• uniform motion
• none of the above

Solution

The motion of a freely falling body is an example of uniformly accelerated motion.

Q18. If a particle is moving in a spiral path with constant speed, then:

• its displacement is zero
• magnitude of acceleration is constant
• The velocity of the particle remains constant
• Magnitude of acceleration decreases continuously

Solution

As the particle is moving in spiral path with constant speed, its magnitude remains constant whereas direction changes continuously.  Thus, the magnitude of acceleration also remains constant.

Q19. On acceleration-time graph the area under the curve equals the:

• Displacement
• Change in velocity
• Change in acceleration
• Meaningless

Solution

The area between the a-t graph and the time-axis gives the change in velocity.

Q20. The kinematic equation of motion v = u+at is not applicable if :

• acceleration is not constant
• velocity is not constant
• displacement is not constant
• motion is non-uniform.

Solution

It is applicable if acceleration (a) is constant.

Q21. What does the slope of a velocity - time represent?

• Displacement
• Momentum
• Acceleration
• Distance

Solution

The slope of a velocity - time represent acceleration.

Q22. The speed of an object in a particular direction is called

• uniform speed
• velocity
• distance
• displacement

Solution

The speed of an object in a particular direction is called velocity.

Q23. Which of the following measurements could be a velocity?

• 5 m North  
• 5 m/s North  
• 5 s North  
•     5 m/s²  

Solution

5m/s north is a velocity.  

Q24. A body of mass 1kg and 10kg are dropped simultaneously from the top of a tower. The ratio of the time taken by them to reach the ground is

• 1:1
• 1:10
• 10:1
• 9.8:98

Solution

1:1, the time taken does not depend on the mass of the falling object.

Q25. The acceleration at any instant is the slope of the tangent of the _______curve at that instant:

• x-t
• v-t
• a-t
• x-v

Solution

 The v-t graph and this can also be verified dimensionally.

Q26. What is the distance of the star (in km) from which a light takes 3 x 10⁹ year to reach the earth? The speed of light, is C = 3 x 10⁸ m/s.

• 2.838 ×  10²² km
• 2.388 ×  10²² km
• 2.888 ×  10²² km
• 2.808 ×  10²² km

Solution

Time = 3 x 10⁹ x 365 x 24 x 60 x 60 = 9.46 x 10¹⁶ s Distance = speed x time = 3 x 10⁸ m/sx 9.46 x 10¹⁶ s =   2.838 x 10²² km

Q27. The magnitude of displacement is equal to minimum possible distance between two positions.

• True  
• False  
• sometimes true and sometimes false  
• can’t predict

Solution

Answer is true.        

Q28. The slope of velocity-time graph gives:

• Distance
• Displacement
• Speed
• Acceleration

Solution

The rate of change of velocity is acceleration

Q29. On velocity-time graph when two curves coincide, the objects will have

• Different velocity
• Same velocity
• Same acceleration
• Different acceleration

Solution

On velocity-time graph, the point at which two curves coincide will indicate that both the objects have same velocity at that instant.

Q30. A boy throws up a ball in a stationary lift and the ball returns to his hands in 10 s. Now if the lift starts moving up at a speed of 5 m/s. The time taken for a ball thrown straight up to return to his hands is:

• less than 10 s
• more than 10 s
• equal to 10 s
• insufficient information given

Solution

The uniform velocity of the lift does not affect the relative velocity of the ball with respect to the boy. So, the ball will still return in 10 s.

Q31. Choose the incorrect statement

• Time rate of change of displacement is called velocity
• Velocity is a vector quantity
• Velocity gives no idea about the direction of motion of the objects
• Velocity can be positive, negative or zero

Solution

Velocity tells us the direction of motion of objects.

Q32. If in case of a motion, displacement is directly proportional to the square of time elapsed, what do you think about its (A) velocity (B) acceleration?

• Velocity varies inversely with time and acceleration is a constant.
• Velocity proportional to square of time and acceleration is constant.
• Both velocity and acceleration are proportional to square of time.
• Velocity varies linearly with time whereas acceleration is constant.

Solution

So velocity varies linearly with time and acceleration is a constant.

Q33. If the signs of the velocity and acceleration of a particle are the same, the speed of the particle ______________.

• Decreases  
• Increases  
• Remains same  
• Cannot conclude anything  

Solution

If velocity and acceleration point in the same direction,  the object speeds up.

Q34. If a body does not change its direction during the course of its motion, then

• Path length and displacement are equal
• Path length is greater than displacement
• Displacement is greater than path length
• Path length is either greater or equal to displacement

Solution

Path length and displacement becomes equal if an object does not change its direction.

Q35. Which of the following statements about distance is true:

• It cannot be positive
• It cannot be zero
• It can never be less than magnitude of displacement
• It always decreases with time

Solution

Distance is always equal to or more than the magnitude of displacement.

Q36. A car moving with a speed of 50 km/h can be stopped by applying brakes after at least 10 m. At what rate the velocity is decreasing in the motion?

• - 20.2 m/s²
• 30 m/s²
• - 9.6 m/s²
• 25.4 m/s²

Solution

Q37. The displacement of a particle starting from rest (at t = 0) is given by s = 6t²-t³ The time in seconds at which the particle will attain zero velocity again, is

• 2
• 4
• 6
• 8

Solution

 Here t = 0 is not realistic so at t = 4s the velocity will be zero.        

Q38. A particle is moving along a circle of radius R such that it completes one revolution in 40 seconds. What will be the displacement after 2 minutes 20 seconds?

• R
• 4R
• 6R
• 2R

Solution

1 revolution in 40 seconds In 1 second it covers = 1/40 revolution

Q39. For uniform circular motion:

• velocity is along circle and acceleration is towards the centre of circle
• velocity and acceleration is towards the centre of circle
• velocity is along tangent and acceleration is towards the centre of circle
• velocity and acceleration is along the tangent

Solution

For uniform circular motion, velocity is along tangent and acceleration is towards the centre of circle.

Q40. Two stones of different masses are thrown vertically upward with same initial velocity. Which one will rise to a greater height?

• Stone of lower mass
• Stone of higher mass
• Both will rise to the same height
• Information given is insufficient