Laws Of Motion And Gravitation Class 10th Science Tamilnadu Board Solution

Class 10th Science Tamilnadu Board Solution
Part-a
  1. The acceleration in a body is due to ___________. i) balanced force ii) unbalanced force…
  2. The physical quantity which is equal to the rate of change of momentum isA. displacement…
  3. The momentum of a massive object at rest is _______.A. very large B. very small C. zero D.…
  4. The mass of a person is 50 kg. The weight of that person on the surface of the earth will…
  5. The freezing of biotechnology products like vaccines require ________ freezing system.A.…
  6. Two objects of same mass, namely A and B hit a man with a speed of 20 km/hr and 50 km/hr…
  7. An object is moving with a velocity of 20 m/s. A force of 10 N is acting in a direction…
  8. Assertion (A): Liquefied cryogenic gases are sprayed on electric cables in big cities.…
  9. The acceleration due to gravity on the surface of the earth will be maximum at ________…
  10. If the radius of the earth is reduced to half of its present value, with no change in the…
  11. Selvi placed her purse on the passenger’s seat of her car when she drove to work. By the…
  12. Why does a fielder in the game of cricket pull his hands back when he catches a ball?…
  13. From the following statements, choose that which is not applicable to the mass of an…
  14. List out the names of the organisations which are not associated with Chandrayaan-I…
Part-b
  1. If force = mass x acceleration, then momentum = __________. Fill in the blanks.…
  2. If liquid hydrogen is for rocket, then _________ is for MRI. Fill in the blanks.…
  3. Correct the mistakes, if any, in the following statements. i) One newton is the force that…
  4. The important use of cryogenics is cryogenic fuels. What do you mean by cryogenic fuels?…
  5. As a matter of convention, an anticlockwise moment is taken as ________ and a clockwise…
  6. A bullet of mass 20 g moving with a speed of 75 ms-1 hits a fixed wooden plank and comes…
  7. A shopping cart has a mass of 65 kg. In order to accelerate the cart by 0.3ms-2 what force…
  8. Why does a spanner have a long handle?
  9. Why does a boxer always move along the direction of the punch of the opponent?…
  10. The mats used in gyms and the padding used in sports uniforms are made up of soft…
  11. Write two principles that are used in rocket propulsion.
  12. A 10 Kg mass is suspended from a beam 1.2 m long. The beam is fixed to a wall. Find the…
  13. If the force experienced by a body of unit mass is gravitational field strength, find the…
  14. If the density of the earth is doubled to that of its original value, the radius remaining…
  15. Find the acceleration due to gravity. Renu is standing in a dining line 6.38 x 10^3 km…
  16. Will the value change after she finishes her lunch? Renu is standing in a dining line 6.38…
  17. If an angel visits an asteroid called B 612 which has a radius of 20 m and mass of 104 kg,…
  18. A man of mass ‘m’ standing on a plank of mass ‘M’ which is placed on a smooth horizontal…
  19. Two balls of masses in ratio 2:1 are dropped from the same height. Neglecting air…
  20. An object of mass 1 kg is dropped from a height of 20 m. It hits the ground and rebounds…
  21. What will be the acceleration due to gravity on the surface of the moon, if its radius is…
  22. A boy weighing 20 kg is sitting at one end of a see-saw at a distance of 1.2 m from the…
  23. A cart driver prods his horse to move forward. The horse refuses to budge and explains:…
Part-c
  1. Space Stations are used to study the effects of long-space flight on the human body.…
  2. is the mathematical form of Newton’s law of gravitation, G - gravitational constant, m1m2,…
  3. Newton’s first law of motion gives a qualitative definition of force. Justify.…
  4. The figure represents two bodies of masses 10 kg and 15 kg, moving with an initial…
  5. A 5 N force acts on a 2.5 kg mass at rest, making it accelerate in a straight line. (i)…
  6. State the law of conservation of momentum. Two billion people jump above the earth’s…
  7. State Newton’s law of gravitation. Write an expression for acceleration due to gravity on…
  8. A bomb of mass 3 kg, initially at rest, explodes into two parts of 2 kg and 1 kg. The 2 kg…
  9. Two ice skaters of weight 60 kg and 50 kg are holding the two ends of a rope. The rope is…

Part-a
Question 1.

The acceleration in a body is due to ___________.

i) balanced force ii) unbalanced force

iii) electro static force


Answer:

(ii) is correct.

In case of (i), balanced forces lead to zero net force. So, there is no acceleration as F = ma. For (iii), the force acts only on charged bodies. In most everyday objects, there are no excess charges and they are neutral bodies. So electrostatic force causes no acceleration on uncharged bodies. For (ii), there is a net force, so there is acceleration.



Question 2.

The physical quantity which is equal to the rate of change of momentum is
A. displacement

B. acceleration

C. force

D. impulse


Answer:

By Newton’s second law, force is defined as the rate of change of momentum. So (iii) is correct. Displacement is the rate of change of position. Acceleration is the rate of change of velocity. Impulse measures the impact of a force, given by force multiplied by time.


Question 3.

The momentum of a massive object at rest is _______.
A. very large

B. very small

C. zero

D. infinity


Answer:

Momentum is given by the product of mass and velocity. Since the body is at rest, velocity is zero. Hence, momentum is zero.


Question 4.

The mass of a person is 50 kg. The weight of that person on the surface of the earth will

be ________.
A. 50 N

B. 35 N

C. 380 N

D. 490 N


Answer:

W = mg,

where W is the weight,


m is the mass,


and g is acceleration due to gravity, which is 9.8 m/s2.


So weight is equal to 50 kg × 9.8 m/s2 = 490 N.


Question 5.

The freezing of biotechnology products like vaccines require ________ freezing system.
A. Helium

B. Nitrogen

C. Ammonia

D. Chlorine


Answer:

Liquid N2 can achieve temperatures as low as -196 degrees C. It’s cryogenic. This allows preservation. Moreover, though liquid He is also cryogenic, it leads to formation of ice crystals which may damage the biotechnology products.


Question 6.

Two objects of same mass, namely A and B hit a man with a speed of 20 km/hr and

50 km/hr respectively and comes to rest instantaneously. Which object will exert more force on that man? Justify your answer.


Answer:

Let both have a mass of m.

Momentum of A = mass × velocity = 20m


Momentum of B = 50m


Force is defined as the rate of change of momentum. Since both A and B come to rest instantaneously, B exerts a greater force because it has greater momentum.



Question 7.

An object is moving with a velocity of 20 m/s. A force of 10 N is acting in a direction perpendicular to its velocity. What will be the speed of the object after 10 seconds?


Answer:

The velocity will still be 20 m/s. The force acts perpendicular to the velocity hence it has no component in the direction of motion and thus has no effect on the motion.


Question 8.

Assertion (A): Liquefied cryogenic gases are sprayed on electric cables in big cities.

Reason(R): Liquefied cryogenic gases prevent wastage of power.
A. A is incorrect and R is correct.

B. A is correct and R is incorrect

C. Both A and R are incorrect.

D. A is correct and R supports A.


Answer:

In big cities, it is difficult to set up overhead cables. So power cables are placed underground. But underground cables get heated up and this leads to power loss as well as rise in resistance of wires due to such temperature rise which leads to further power loss. So liquefied cryogenic gases are sprayed on the cables to cool them and prevent wastage of power.


Question 9.

The acceleration due to gravity on the surface of the earth will be maximum at ________ and minimum at _________


Answer:

The earth is an oblate spheroid. This means that the radius is least near the poles and maximum near the equator. Since the acceleration due to gravity on the surface of the earth is inversely proportional to the square of the radius, g is maximum at the poles and minimum at the equator.