If the velocity of a body becomes two times its initial velocity, its kinetic energy becomes n times its initial kinetic energy. What is the value of n?

Simplify the value of $$\frac{{{\text{0}}{\text{.9}} \times {\text{0}}{\text{.9}} \times {\text{0}}{\text{.9 + 0}}{\text{.2}} \times {\text{0}}{\text{.2}} \times {\text{0}}{\text{.2 + 0}}{\text{.3}} \times {\text{0}}{\text{.3}} \times {\text{0}}{\text{.3}} - {\text{3}} \times 0.9 \times {\text{0}}{\text{.2}} \times {\text{0}}{\text{.3}}}}{{{\text{0}}{\text{.9}} \times {\text{0}}{\text{.9 + 0}}{\text{.2}} \times {\text{0}}{\text{.2 + 0}}{\text{.3}} \times {\text{0}}{\text{.3}} - 0.9 \times {\text{0}}{\text{.2}} - {\text{0}}{\text{.2}} \times {\text{0}}{\text{.3}} - 0.3 \times 0.9}} = ?$$

A

1.4

B

0.054

C

0.8

D

1.0

If the velocity of an object becomes twice that of its initial velocity, then its kinetic energy become n times of its initial kinetic energy. Then what would be the value of n?

A

3

B

4

C

$$\frac{1}{2}$$

D

6

$$\frac{{38 \times 38 \times 38 + 34 \times 34 \times 34 + 28 \times 28 \times 28 - 38 \times 34 \times 84}}{{38 \times 38 + 34 \times 34 + 28 \times 28 - 38 \times 34 - 34 \times 28 - 38 \times 28}}$$ is equal to = ?

A

24

B

32

C

44

D

100

The kinetic energy of a man is half that of a boy whose mass is half that of the man. When the man speeds up by 5 m/s, his kinetic energy doubles that of the boy’s kinetic energy. What is the initial velocity of the man?

A

5 m/s

B

10 m/s

C

15 m/s

D

20 m/s

Two refrigerators M and N operate in series. The refrigerator M absorbs energy at the rate of 1 kW from a body at temperature 400 K and rejects energy as heat to a body at a temperature T. The refrigerator N absorbs the same quantity of energy which is rejected by the refrigerator N from the body at temperature T, and rejects energy as heat to a body at temperature 800 K. If both the refrigerators have the same C.O.P., what is the value temperature T?

A

600 K

B

200 K

C

565.68 K

D

459.21 K

A stone has initial potential, kinetic and internal energy 7 J, 10 J and 2x J respectively, if the final kinetic energy, potential energy and internal energy are 5 J, 21 J and x respectively, what is the final internal energy?

A

2 J

B

4 J

C

5 J

Match the following Device Conversion of Energy (a) Windmill (i) Chemical Energy to electrical energy (b) Bulb (ii) Kinetic Energy to Electrical Energy (c) Electrical Cell (iii) Sound Energy to Electrical energy (d) Microphone (iv) Electrical Energy to Light Energy

A

(a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)

B

(a) - (ii), (b) - (iv), (c) - (i), (d) - (iii)

C

(a) - (ii), (b) - (iii), (c) - (i), (d) - (iv)

D

(a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)

The kinetic energy of a body becomes four times of its initial value, then new momentum will ___________

A

Become twice its initial value

B

Become thrice its initial value

C

Become four times its initial value

D

Remains constant

If the kinetic energy of a body becomes 256 times its initial value, then the new linear momentum will be

A

8 times the initial value

B

16 times the initial value

C

the same as the initial value

D

32 times the initial value

In which of the following case we can surely say that the body A is charged: a) When a positively charged body is kept near to body A and it gets attracted b) When a negatively charged body is kept near to body A and it gets attracted c) When a positively charged body is kept near to body A and it gets repelled

A

Only in case a the body A is surely charged

B

Only in case b the body A is surely charged

C

Only in case c the body A is surely charged

D

In all the cases a, b and c the body A is surely charged

If the velocity of a body becomes two times its initial velocity, its kinetic energy becomes n times its initial kinetic energy. What is the value of n?

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