Kinematics (NEET (NTA)National Eligibility cum Entrance Test (Medical) Physics): Questions 73  76 of 233
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Question number: 73
» Kinematics » Motion in a Straight Line
Question
A man can swim with velocity v relative to water. He has to cross a river of width d flowing with a velocity u (w > v). The distance through which he is carried downstream by the river is x. Which of the following statements is correct?
Choices
Choice (4)  Response  

a.  If he crosses the river in minimum time x = du/v 

b.  x cannot be less than du/v 

c.  Force to be minimum he has to swim in a direction making an angle of π/2 sin 1 (v/u) with the direction of the flow of water. 

d.  x will be maximum if he swims in a direction making an angle of π/2 + sin1  1 (v/u) with direction of the flow of water. 

Question number: 74
» Kinematics » Scalars and Vectors » Scalar and Vector Products
Assertion (Ꭺ)
IfA + B= AB , then angle between A and B is 90°
Reason (Ꭱ)
A + B = B + A
Choices
Choice (4)  Response  

a.  Both Ꭺ and Ꭱ are false 

b.  Ꭺ is false but Ꭱ is true 

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

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

Question number: 75
» Kinematics » Scalars and Vectors » Scalar and Vector Products
Question
The three vectors A = 3i  2j  k, B = i  3j + 5k and C = 2i  j  4k does not form
(1) an equilateral triangle
(2) isosceles triangle
(3) a right angled triangle
(4) no triangle
Choices
Choice (4)  Response  

a.  1 and 2 are correct 

b.  2 and 4 are correct 

c.  1,2 and 3 are correct 

d.  1 and 3 are correct 

Question number: 76
» Kinematics » Scalars and Vectors » Scalar and Vector Products
Question
A boy walks uniformly along the sides of a rectangular park of size 400 m x 300 m, starting from one corner to the other corner diagonally opposite. Which of the following statements is correct?
(1) He has travelled a distance of 700 m
(2) His displacement is 500 m
(3) His velocity is not uniform throughout the walk
(4) His displacement is 700 m
Choices
Choice (4)  Response  

a.  1 and 3 are correct 

b.  1,2 and 3 are correct 

c.  2 and 4 are correct 

d.  1 and 2 are correct 
