KinematicsAverage Speed and Instantaneous Velocity (NEET Physics): Questions 64  67 of 108
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Question number: 64
» Kinematics » Average Speed and Instantaneous Velocity
Question
A disc of mass 5 gm is kept horizontally in air by firing bullets of mass 10 g each at the rate of 20/s. If the bullets rebound with same speed. The velocity with which the bullets are fired is –
Choices
Choice (4)  Response  

a.  9.28 cm/s 

b.  1.25 cm/s 

c.  1.96 cm/s 

d.  4.89 cm/s 

Question number: 65
» Kinematics » Average Speed and Instantaneous Velocity
Question
A swimmer who can swim in a river with speed mv (with respect to still water) where v is the velocity of river current, jumps into the river from one bank to cross the river. Then
Select the correct answers and mark it according to the following codes:
(1) If m < 1 he cannot cross the river
(2) If m < 1 he cannot reach a point on other bank directly opposite to his starting point.
(3) If m > 1 he can reach a point on other bank
(4) He can reach the other bank at some point, whatever be the value of m.
Choices
Choice (4)  Response  

a.  1 and 2 are correct 

b.  1, 2 and 3 are correct 

c.  2 and 4 are correct 

d.  1 and 3 are correct 

Question number: 66
» Kinematics » Average Speed and Instantaneous Velocity
Assertion (Ꭺ)
Rain is falling vertically downwards with velocity 6 km/h. A man walks with a velocity of 8 km/h. Relative velocity of rain w. r. t. the man is 10 km/h.
Reason (Ꭱ)
Relative velocity is the ratio of twovelocities.
Choices
Choice (4)  Response  

a.  Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ 

b.  Both Ꭺ and Ꭱ are false 

c.  Ꭺ is true but Ꭱ is false 

d.  Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ 

Question number: 67
» Kinematics » Average Speed and Instantaneous Velocity
Question
A body of mass 0.05 kg falls from a height of 5 meter into a pile of sand. The body penetrates the sand a distance of 5 cm before stopping. What force has the sand exerted on the body?
Choices
Choice (4)  Response  

a.  49 N 

b.   19.6 N 

c.  196 N 

d.  0.196 N 
