# 10th Science Unit 1 Book Back Answer

## Samacheer Kalvi 10th Science Unit 1 Book Back Questions with Answers:

Samacheer Kalvi 10th Std  Science Book Back 1 Mark and 2 Mark Questions with Answers PDF in Science uploaded and available below. 10th Standard New Science Syllabus 2022 – Physics 1 Laws of Motions Science Book Back Answers available for both English and Tamil mediums. Tamil Nadu Samacheer Kalvi 10th Science Book Portion consists of  23 Units. Science Book Contain Physics 01- 06, Chemistry 07 – 11, Biology 12 – 22 and Visual Communications  23 units. Check Unit-wise and Full Class 10th Science Book Back Answers/ Guide 2022 PDF format for Free Download for both English and Tamil Medium. Samacheer Kalvi 10th Science Book back Solutions/Answers below:

English, Tamil, Maths, Social Science, and Science Book Back One and Two Mark Questions and Answers available in PDF on our site. Class 10th Standard Science Book Back Answers and 10th Science Solution guide Book Back Answers PDF. See below for the New 10th Science Book Back Questions with Answer PDF:

Samacheer Kalvi 10th Science Book Subject One Mark, Two Mark Guide questions and answers are available below. Check Science Book Back Questions with Answers. Take the printout and use it for exam purposes.

### 10th Science Book Back Answers

#### Unit 1 – Laws of Motions

1. Inertia of a body depends on
a. weight of the object     b. acceleration due to gravity of the planet
c. mass of the object        d. Both a & b
Ans: (c) mass of the object

2. Impulse is equal to
a. rate of change of momentum b. rate of force and time
c. change of momentum d. rate of change of mass
Ans: (c) change of momentum

3. Newton’s III law is applicable
a. for a body is at rest      b. for a body in motion
c. both a and b                  d. only for bodies with equal masses
Ans: (c) both (a) & (b)

4. Plotting a graph for momentum on the X-axis and time on Y-axis. the slope of momentum- time graph gives
a. Impulsive force     b. Acceleration
c. 1/Force                   d. Rate of force
Ans: (c) 1/F)

5. In which of the following sport the turning of effect of force used
a. swimming b. tennis c. cycling d. hockey

Ans: (c) cycling

6. The unit of ‘g’ is m s-2. It can be also expressed as
a. cm s–1 b. N kg–1 c. N m2 kg–1 d. cm2 s–2

Ans: (b) N Kg–1

7. One-kilogram force equals to
a. 9.8 dyne   b. 9.8 × 104 N    c. 98 × 104 dyne    d. 980 dyne
Ans: (c) 98 × 104 dyne

8. The mass of a body is measured on planet Earth as M kg. When it is taken to a planet of radius half that of the Earth then its value will be kg
a. 4 M    b. 2M    c. M/4     d. M
Ans: (c) M/4

9. If the Earth shrinks to 50% of its real radius its mass remaining the same, the weight of a body on the Earth will
a. decrease by 50%    b. increase by 50%     c. decreases by 25%     d. increase by 300%
Ans: (c) decrease by 25%

10. To project the rockets which of the following principle(s) is /are required?
a. Newton’s third law of motion          b. Newton’s law of gravitation
c. law of conservation of linear momentum  d. both a and c
Ans: (d) both (a) and (c)

II. Fill in the blanks:
1. To produce a displacement is required. Ans : Force
2. Passengers lean forward when sudden brake is applied in a moving vehicle. This can be explained by . Ans : Inertia of motion
3. By convention, the clockwise moments are taken as and the anticlockwise moments are taken as . Ans: Negative, Positive
4. is used to change the speed of car. Ans: Gears
5. A man of mass 100 kg has a weight of at the surface of the Earth. Ans: 980 N

III. True or False (Correct the Statement if it is false):

1. The linear momentum of a system of particles is always conserved.
Ans: False. The linear momentum of a system of particles is always conserved only if no external force is applied.

2. Apparent weight of a person is always equal to his actual weight.
Ans: False. Apparent weight and actual weight is not equal during upward or downward motion.

3. Weight of a body is greater at the equator and less at the polar region.
Ans: False. Weight of a body is lesser at the equator and more at the polar region
as g α 1 R2.

4. Turning a nut with a spanner having a short handle is so easy than one with a long handle.
Ans: False. Moment of force in longer handle is easy than one with a short handle.

5. There is no gravity in the orbiting space station around the Earth. So the astronauts feel weightlessness.
Ans: False. Apparent weight is zero. They are in a state of weightlessness.

IV. Match the following:

 Column I Column II 1. Newton’s I law (a) Propulsion of a rocket 2. Newton’s II law (b) Stable equilibrium of a body 3. Newton’s III law (c) Law of force 4. Law of conservation of linear momentum (d) Flying nature of a bird

1. (b) Stable equilibrium of a body
2. (c) Law of force
3. (d) Flying nature of a bird
4. (a) Propulsion of a rocket

V. Assertion and Reason:
Mark the correct choice as
a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
c) Assertion is true, but the reason is false.
d) Assertion is false, but the reason is true.
Assertion: The sum of the clockwise moments is equal to the sum of the anticlockwise moment.
Reason: The principle of conservation of momentum is valid if the external force on the system is zero.
Ans: (b) both the assertion and the reason are true, but the reason is not the correct explanation of the assertion

Assertion: The value of ‘g’ decreases as height and depth increases from the surface of the Earth.
Reason:  ‘g’ depends on the mass of the object and the Earth.
Ans : (c) Assertion is true, but the reason is false.