# NEET Physics: Questions 128 - 131 of 2142

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## Question number: 128

MCQ▾

### Question

The length of second’s hand in watch is 1 cm. The change in velocity of its tip in 15 seconds is

### Choices

Choice (4) Response

a.

zero

b.

cm/sec

c.

cm/sec

d.

cm/sec

## Question number: 129

MCQ▾

### Question

A person aiming to reach the exactly opposite point on the bank of a stream is swimming with a speed of 0.5 m/s at an angle of 120° with the direction of flow of water. The speed of water in the stream is

### Choices

Choice (4) Response

a.

lm/s

b.

0.433 m/s

c.

0.25 m/s

d.

0.5 m/s

## Question number: 130

MCQ▾

### 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 + sin-1 - 1 (v/u) with direction of the flow of water.

## Question number: 131

» Kinematics » Scalars and Vectors » Scalar and Vector Products

Assertion-Reason▾

### Assertion (Ꭺ)

If|A + B|=| A-B| , then angle between A and B is 90°

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

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