Question

21st October, 2020 JESUS AND MARY SCHOOL AND COLLEGE

HALF YEARLY EXAMINATION 2020 – 2021

CLASS 10

TIME: 2HRS. PHYSICS MAX. MARKS – 60

1. This exam should be conducted under strict parental supervision and guidance.

2. Do this exam in TEST SHEETS only and submit the same on Tuesday (27th October, 2020) for checking.

3. This paper is divided into two sections – Section A and Section B. Attempt all questions from Section A and any four questions from Section B.

SECTION A (30 Marks)

Attempt all questions in this section

Question 1: [5 M]

a. What do you mean by kgf and write its relation with Newton?

b. What is axis of rotation?

c. Which types of motions are exhibited by a vehicle and its wheels?

d. Express SI unit of work in terms of the fundamental units of mass, length and time.

e. What is the amount of workdone of an object if the force acting on is 10 kgf and the displacement is 10 m.(g=10m/s2)

Question 2: [5 M]

a. Name the device used for measuring mass.

b. Write the circumstances in which work done by a force is zero.

c. What is the relation between SI and CGS unit of work.

d. By what factor does the kinetic energy of a moving body change when its speed is reduced to half?

e. What is power? How is it related to energy?

Question 3: [5 M]

a. Mention one practical use of echo.

b. What is amplitude?

c. What is energy?

d. Two astronauts on the surface of moon cannot talk to each other. Why?

e. In the above question what type of hearing aids are required to them?

Question 4: [5 M]

a. What is the minimum distance for an echo to be occurred?

b. During lightening, first we observe light and then hear sound. Why?

c. What is pitch?

d. On what factor pitch is depending?

e. What is power? How is it related to energy?



SECTION B (40 Marks)

Attempt any four questions from this section

Question 4:

a. What do you understand by the terms: (i) wavelength (ii) frequency and (iii) time period [3 M]

b. What factor determines the loudness of a sound wave? Explain with an example. [3 M]

c. A man standing between two cliffs produces a sound and bears two successive echoes at intervals of 3 s and 4 s respectively. Calculate the distance between two cliffs. The speed of sound in air is 330 m/s. [4 M]

Question 5:

a. Name the main energy transformations that occur in the following :

(i) An electric fan (ii) A steam engine (iii) A washing machine [3 M]

b. A bullet fired from the gun is able to penetrate a wooden block. Why? [3 M]

c. A boy of mass 0.2 kg falls from a height of 10 m to a height of 6 m above the ground. Find the loss in potential energy taking place in the body. [4 M]

Question 6:

a. Give at least three differences between light and sound wave. [3 M]

b. What are the characteristics of sound wave? [3 M]

c. A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears the echo from a cliff after 8 vibrations of the pendulum. If the velocity of sound in air is 340 m/s, what is the distance between the cliff and the observer? [4 M]

Questions 7:

a. Where does the position of centre of gravity lie for: (i) circular lamina (ii) a triangular lamina [3 M]

b. A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in 4 minutes and a girl weighing 30 kgf does the same in 3 minutes. Compare: (i) The work done by them (ii) The power developed by them. [4 M]

c. What is wave velocity? On what factors it depends? [3 M]



Question 8:

a. Which characteristic of sound will change if there is a change in (i) its amplitude (ii) its waveform [3 M]

b. Two wave of same pitch have their amplitudes in the ratio 2:3. [4 M]

(i) What will be the ratio of their loudness?

(ii) What will be the ratio of their frequencies?

c. A radar sends a signal to an aircraft at a distance of 30 km away and receives it back after

2 x 10-4 s. What is the speed of the signal? [3 M]

challenge for you guy's

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Answer 1

Answer:

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