NIOS Class 10 Science & Technology Chapter 13 Solution – Work And Energy
NIOS Class 10 Science & Technology Solution Chapter 13 Work And Energy. NIOS Class 10 Science & Technology Chapter 13 Question Answers Download PDF. NIOS Class 10 Science Notes.
NIOS Class 10 Science & Technology Chapter 13 Solution
Board | NIOS |
Class | 10th (Secondary) |
Subject | Science and Technology (213) |
Topic | Question Answer, Solution, Notes |
CHAPTER: – 13
(WORK AND ENERGY)
INTEXT QUESTIONS 13.1
Choose the correct option
1) (i) Work done is zero:
(a) When force and displacement are in the same direction.
(b) When force and displacement of the body are in opposite directions.
(c) When force acting on the body is perpendicular to the direction of the displacement of the body.
(d) When force makes an angle with displacement.
Ans: – Option (c).
(ii) 1 J of work is done when a force of 0.01 N moves a body through a distanceof :
a) 0.01 m (b) 0.1 m (c) 1 m (d) 10 m (e) 100 m.
Ans: – option (e).
(iii) In which of the following situations work is done?
(a) A person is climbing up a stair case.
(b) A satellite revolving around the earth in closed circular orbit
(c) Two teams play a tug of war and both pull with equal force
(d) A person is standing with heavy load on his head.
Ans: – Option (a).
2) A car of mass 500 kg is moving with a constant speed of 10 ms–1on a rough horizontal road. Force expended by the engine of the car is 1000 N. Calculate work done in 10 s by:
(a) net force on the car (b) gravitational force
(c) the engine (d) frictional force.
Ans: – As we know, Force= mass×acceleration
Here, acceleration=0,
So, Net force on the car is 0.
Gravitational force = mg
Here, m=500kg, g=10.
So, gravitational force= 500×10= 5000N.
As we know frictional force,
net force= force of engine – f,
or, 0=1000 – f,
or, f=1000N.
INTEXT QUESTIONS 13.2
1) Explain the terms work and energy with one example each.
Ans: – Works: – The term work is used when there is a displacement if an object by applying some amount of force to it.
Energy: – The energy is considered as the efficiency of doing some work.
2)The ability to do work is called …energy…………
3)The SI unit of all forms of energy is …joule…………
4)Energy possessed by a spring is ……potential……… energy.
5)The energy possessed by a body due to its position is called ……potential………energy.
6)The energy possessed by a body due to its motion is called ……kinetic ……… energy.
7)At height h the potential energy is Ep at height 2h the potential energy wouldbe ……Ep/2……… (As potential energy is equal to mgh)
8)At height h the potential energy of a body of mass m is Ep. At the same height the potential energy of a body of mass 2m would be ……Ep/2………(Ep=mgh)
9)A body of mass m moving with a speed v has kinetic energy, Ek. The bodyif moves with speed 2v, will have kinetic energy equal to ……Ek/4……… (As Ek=1/2mv^2.)
10) A body of mass m moving with a speed v has kinetic energy Ek. A body of mass 2m moving with the same speed will have a kinetic energy……2Ek……
INTEXT QUESTIONS 13.3
Give one example each of the following energy transformations.
1)
(i) Light energy into chemical energy.
Ans: – Photosynthesis.
(ii) Chemical energy into heat.
Ans: – Exothermic reaction.
(iii) Chemical energy into electrical energy.
Ans: – Nuclear power station.
(iv) Mechanical energy into electrical energy.
Ans: – Generator.
(v) Thermal energy into electrical energy.
Ans: – Coal power plant.
(vi) Light energy into electrical energy.
Ans: – Solar panel.
2) (i) A motor converts electrical energy into ……… mechanical energy…………
(ii) An electric heater converts electrical energy into ………heat energy…………
(iii) A microphone converts sound energy into …….. electrical energy………….
(iv) A loudspeaker converts sound energy into …… electrical energy……………
(v) A heat engine converts heat energy into …….. mechanical energy………….
(vi) When we rub our hands together, we change work into ………heat energy……….
INTEXT QUESTIONS 13.4
1) Kamya climbs up a staircase in 5 minutes, Suraiya takes only 3 minutes in goingup the same staircase. The weight of Kamya is equal to the weight of Suraiya.
(i) Which of the two does more work?
Ans: – As we know that work(W)= force × displacement;
And the force= mass×acceleration.
So, the weight of both as same then kamya will works more as displacement is more.
(ii) Which of the two spends more power?
As: – As work of Kamya is more than Suriya so kamya will spends more power.
2) Express 1.5 H.P. in SI Unit of power.
Ans: – As we know, 1HP=746 watt.
so, 1.5 HP= 1.5 × 746= 1119 watt.
3) One cricket ball and One plastic ball are dropped from the same height. Which will reach the ground with(a) more energy, (b) less power?
Ans: – We all know that the energy is dependent on the mass of the object so the cricket ball which has the more weight will have more energy. The ball made up of plastic has law amount of mass compared to cricket ball so the plastic ball has less power.
TERMINAL EXERCISE
1) Define the following terms and give their SI units. (a) Work (b) Power (c) Energy.
Ans: – Works: – The term work is used when there is a displacement if an object by applying some amount of force to it. Its SI unit is N-S.
Power: – Power is denotes by the amount of work done in a certain time. The unit of power is watt.
Energy: – The energy is considered as the efficiency of doing some work.
2) List different forms of energy.
Ans: – The different forms of energy are thermal energy, heat energy, electrical energy, solar energy, wind energy.
3)State Law of Conservation of Energy. Explain with the help of examples.
Ans: – As we know the energy is conserve from one source to the other sources to the other source and in the whole way it is constant.
4)List the energy transformation taking place in a thermal power plant.
Ans: – In a thermal power plant the coal is heated up then the electricity is produced. In this process at first the heat energy is produced then this heat energy is transformed to electrical energy.
5)A ball of mass 0.5 kg has100 J of kinetic energy. What is the velocity of theball?
Ans: – As we know, kinetic energy (Ek)= 1/2mv^2;
Or, 100=1/2×0.5×v^2;
Or, v=20m/s.
6) A body of mass 100 kg is lifted up by 10 m. Find
(a) The amount of work done.
(b) Potential energy of the body at that height (g =10 ms–2)
Ans: – The work done, w=F×S,
Here, f=m×a= 100×10=1000; s=10m.
So, w= 1000×10= 10^4 NS.
- Potential energy=mgh,
Here, m=100kg, g=10m/s^2, h=10m.
Potential energy= 100×10×10=10^4.
7) Why Road accidents at high speeds are much worse than the accidents at low speeds?
Ans: – The most of the road accident now a days happen because of the high speed. As we know the kinetic energy is maximum when the speed is high and low when speed is low so more fatal damage happen in case of high kinetic energy.
8) Two bodies of equal mass move with uniform velocities u and 4 u respectively. Find the ratio of their kinetic energies.
Ans: – The kinetic energy=1/2mv^2;
So, kinetic energy id directly proportional to the velocity.
Ek (1)/Ek (2) =¼.
9) What would you like to prefer a ramp or a staircase to reach at the third floorof your hospital? Justify.
Ans: – We always try to do small amount of work for the purpose of working days. In this case as in ramp there is no way of doing heavy works and in stair case the we have to do more works so ramp is preferable.