Question

One mark questions.....

1. kilowatt hour is the unit of?

2. a body of mass 3 kg is dropped from the height of 1m, the kinetic energy of the body will be when it touches the ground?

3. the other name of Nm is ?

4. A 1 kg block is lifted vertically 1m by a boy. the work done by the boy is?

5. a light and heavy body have equal momenta. which one has greater kinetic energy?

6. Newton metre is SI unit of?

7. water stored in a dam possesses what kind of energy?

8. in case of negative work then the angle between the force and displacement is?

9. when a body falls freely towards the Earth then its Total energy is?

10. what is mechanical energy?

thanks ❤

Answer 1

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▶ Question 1 :-)

→ kilowatt hour is the unit of ?

Ans :- Energy .



▶ Question 2 :-)

→ A body of mass 3 kg is dropped from the height of 1m, the kinetic energy of the body will be when it touches the ground?

Ans :- Kinetic energy will be 30 J when it touches to the ground.

➡ Explanation :-

A body of mass 3 Kg is dropped from the height of 1m.

So, potential energy of the body

= mgh

= (3 × 10 × 1) J

= 30J .

When the body touches the ground, it's potential energy becomes zero and because of the conservation of energy, the potential energy gets converted into kinetic energy.

So, the kinetic energy of the object at the ground = potential energy of the body at 1m = 30J

Therefore, the kinetic energy of the body will be 30 J when it touches the ground.



▶ Question 3 :-)

→ The other name of Nm is ?

Ans :- Joules.



▶ Question 4 :-)

→ A 1 kg block is lifted vertically 1m by a boy. the work done by the boy is?

Ans :- Weight = 1kg , distance = 1 m.

We know that :- Force = weight .

→ Weight = mg = 1 × 10 = 10 N. [ Taking g = 10 ]


Then, work done = Force × distance.

= 10 × 1 .

= 10 J.


▶ Question 5 :-)

→ A light and heavy body have equal momenta. which one has greater kinetic energy?

Ans :- The lighter body have greater kinetic energy.

➡ Explanation:-

Let , mass of lighter body = m , and velocity = v

Mass of heavy body = M, and velocity = V

Now since momenta is equal so ,

MV = mv

=> v = MV/m .

Now, KE(L) of lighter body = 1/2 m v^2 = 1/2 m ( MV/m) ^2

KE(H) of heavy mass = 1/2 MV^2

So KE (L) > KE(H)


▶ Question 6 :-)

→ Newton metre is SI unit of?

Ans :- Work done or Energy.


▶ Question 7 :-)

→ Water stored in a dam possesses what kind of energy?

Ans :- Potential energy.


▶ Question 8 :-)

→ In case of negative work then the angle between the force and displacement is?

Ans :- 180° .


▶ Question 9 :-)

→ When a body falls freely towards the Earth then its Total energy is?

Ans :- Since, total energy of the system is always conserved, so when a body falls freely towards the earth, then its total energy remains constant i.e., the sum of the potential energy and kinetic energy of the body would be same at all points.


▶ What is Mechanical energy ?

Ans :- Mechanical energy referred to the sum of potential energy and kinetic energy.



✔✔ Hence, it is solved ✅✅.




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