# IGCSE Physics Paper-1: Specimen Questions with Answers 81 - 83 of 149

## Question number: 81

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MCQ▾

### Question

Find time between shouting and hearing the echo if boy is on an island 300 m away and shouts for help. He hears reply as echo from some cliffs. Consider sound travels at 200 m/s through the air.

Choice (4)

a.

b.

c.

d.

b.

### Explanation

Distance between boy and cliff is 300 m, and he shouted for help but its voice back as echo. So distance travel by voice is 2 ⨯ 300

And the sound travels with speed 200 m/s

## Question number: 82

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### Question

Thumb is placed on bicycle outlet. If air is pushed in what change will occur to pressure and volume?

### Choices

Choice (4)

a.

Pressure decreases, volume decreases

b.

Pressure decreases, volume remains the same

c.

Pressure increases, volume remains the same

d.

Pressure increases, volume decreases

d.

### Explanation

In figure we can see that a student places his thumb on the outlet of a bicycle pump, to stop the air coming out. And direction of the motion of pump increases the pressure and there is no space to coming out to the air, therefore volume will decrease.

## Question number: 83

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### Question

A stopwatch is used to note time of a race is shown in figure. How long did the race take?

Choice (4)

a.

47.0 s

b.

46.0s

c.

46.5s

d.

45.7s