CBSE Work, Energy and Power class 9 Physics assignment

CBSE IX PHYSICS:

1. Under what conditions work is said to be done?

2. State the energy changes taking place in the following cases: (i) A car moves up a hilly road.(ii) a stone projected vertically upward returns

3. Give few examples where energy is possessed by a body due to its change in shape.

4. When we cut a log of wood with a saw it becomes warm, why?

5. Is it possible that force is acting on a body but still work done is zero? Explain.

6.  A rocket of mass 3x106 kg takes off from a launching pad and acquires a vertical velocity of 1 km/s  at an altitude of 25 km. calculate (a) the potential energy and (b) the kinetic energy. (g = 9. 8m/s²)

7.  If a man lifts a load up with the help of a rope such that it raises the load of mass 50 kg  to a height of 20 m in 100 sec. Find the power of man

8.  A ball is dropped from a height of 5m. Find the velocity of the ball just before it reaches the ground.  Do you require the value of mass to find the velocity?

9.  Two persons A and B do same amount of work. The person A does that work in t₁ sec  and the 
person b in t₂ sec. Find the ratio of power delivered by them.

10.  Why do our hands become warm when rubbed against each other? Explain.

11. The kinetic energy of a body of mass 15 kg is 30J. What is its momentum?

12.  Give an example for each of the following energy conversion: (1) electrical energy to kinetic 
energy. (2) Chemical energy to electrical energy (3) sound energy to electrical energy

13.  Two bodies have same momentum. Which will have greater kinetic energy- heavier body or lighter
body?

14.  An electric bulb of 60w is used for 6h per day .Calculate the units of energy consumed in one day 
by the bulb.

15. A boy of mass 50kg runs up to a stair case of 45 steps in 9s. If the height of  a  step is 15cm, find 
his power. (g= 10m/s²)

16.  Two particles of masses 1g and 2g have equal momentum. Find the ratio between their kinetic energies?

17.  What will be the work done by the string, when a stone is tied to a string and whirled in a circle?

18.  A locomotive exerts a force of 7500N and pulls a train through 1.5 km. How much work is done 
by locomotive?

19.  What work a boy of mass 50kg will do in order to increase running speed from  9km/h to 18km/h.

20. The speed of a moving body is halved. What is the change in its K.E.?

Solved CBSE Test papers:

Class 9 Work, Energy ,Power_ Solved Questions - 01

Class 9 Work, Energy ,Power_ Solved Questions - 02

Class 9 Work, Energy ,Power_ Solved Questions - 03

Class 9 Work, Energy ,Power_ Solved Questions - 04

Class 9 Work, Energy ,Power_ Solved Questions - 05

Class 9 Work, Energy ,Power_ Solved Questions - 06          

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CBSE Numerical based on SA For Chapter:Electricity & its effects For (Class X)

1. A resistance of 6 ohms is connected in series with another resistance of 4 ohms. A potential difference of 20 volts is applied across the combination. Calculate the current through the circuit and potential difference across the 6 ohm resistance.


2. Calculate the number of electrons constituting one coulomb of charge per second through any cross section of a conductor.


3. How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V ?


4. How much energy is given to each coulomb of charge passing through a 6 V battery ?


5. Calculate the work done in moving a charge of 5 Coulombs from a point at a potential of 210 Volts to another point at 240 Volts.


7. When a particle of charge 10 µC is brought from infinity to a point P, 2.0 mJ work is done by the external forces. What is the potential at P ?


9. How many electrons pass through a lamp in one minute if the current be 200 mA?

10. Calculate the current supplied by a cell if the amount of charge passing through the cell in 4 seconds is 12 C ?


11. A 2 Volt cell is connected to a 1 Ω resistor. How many electrons come out of the negative terminal of the cell in 2 minutes ?


12. a) How much current will an electric bulb draw from a 220 V source, if the resistance of the bulb filament is 1200 Ω ?

b) How much current will an electric heater coil draw from a 220 V source, if the resistance of the heater coil is 100 Ω ?

13. The potential difference between the terminals of an electric heater is 60 Volts when it draws a current of 4 Ampere from a source. What current will the heater draw if the potential difference is increased to 120 Volt.

14. A torch bulb when cold has 1Ω resistance. It draws a current of 0.3 Ampere when glowing from a source of 3 V. Calculate the resistance of the bulb when glowing and explain the reason for the difference in resistance.

 
15. A current of 0.2 Ampere flows through a conductor of resistance 4.5 Ω. Calculate the potential difference at the ends of the conductor.

5 ways to promote independent thinking

5 ways students can promote their independent thinking:

1. Read Widely: Explore books, articles, and resources from various subjects and genres. Reading broadly exposes you to different perspectives and ideas, stimulating independent thinking.

2. Question Everything: Don't be afraid to ask questions, even if they challenge conventional wisdom. Critical questioning leads to deeper understanding and independent analysis.

3. Self-Directed Learning:Take the initiative to learn beyond the classroom. Pursue topics that genuinely interest you, research them independently, and delve into self-directed projects.

4. Engage in Discussions: Engage in discussions and debates with peers and mentors. Respectfully listen to different viewpoints and defend your own with well-reasoned arguments.

5. Problem-Solving Practice: Challenge yourself with real-world problems and puzzles. Practice finding solutions on your own before seeking help. This builds your problem-solving skills and fosters independence.

By incorporating these strategies into your learning journey, you can enhance your ability to think independently, critically evaluate information, and make informed decisions.

💯JSunil Sir ❤️