Heat

Q.

Heat is equivalent to which of the following quantities?

1. Electric Potential

2. Momentum

3. Charge

4. Energy

Q.

A lead bullet penetrates into a solid object and melts. Assuming that 50% of its kinetic energy was used to heat it, calculate the initial speed of the bullet. The initial temperature of the bullet is ${27}^{\circ }C$ and its melting point is ${327}^{\circ }C$. Latent heat of fusion of lead = $2.5\times {10}^{4}Jk{g}^{-1}$ and specific heat capacity of lead = $125Jk{g}^{-1}{K}^{-1}$.

1. 480 m/s

2. 100 m/s

3. 1000m/s

4. 5000 m/s

Q.

A lead ball at $30{}^{\circ }C$ is dropped from a height of $6.2km$. The ball is heated due to the air resistance and it completely melts just before reaching the ground. The molten substance falls slowly on the ground. Calculate the latent heat of fusion of lead. Specific heat capacity of lead = $126Jk{g}^{-1}{}^{\circ }{C}^{-1}$ and melting point of lead = $330{}^{\circ }C$. Assume that any mechanical energy lost is used to heat the ball. Use $g$ = $10m{s}^{-2}$.

1. $2.4\times {10}^{4}cal/kg$

2. $2.4\times {10}^{4}J/kg$

3. $2.4\times {10}^{5}cal/kg$

4. $4.4\times {10}^{5}J/kg$

Q.

One calorie is the heat energy required to raise the temperature of 1 g of water from _________.

1. ${10}^{\circ }C$ to ${100}^{\circ }C$

2. $1^{\circ }C$ to ${10}^{\circ }C$

3. ${14.5}^{\circ }C$ to ${15.5}^{\circ }C$

4. any initial to any final temperature

Q.

S.I. unit of heat is:

1. Celsius

2. Joule

3. Fahrenheit

4. Calorie

Q.

A spinning wheel A is brought in contact with another wheel B initially at rest. Because of the friction at contact, the second wheel also starts spinning. Heat energy is dissipated.

1. True

2. False

Q. Match the following correctly.

1. Joules
2. $cal{K}^{-1}$
3. Kelvin

Q. One calorie is equal to .

1. $\text{4.5 J}$
2. $\text{4.184 J}$
3. $\text{5 J}$

Q. The S.I. unit of heat was proposed by which scientist?

1. James Watt
2. James Prescott Joule
3. Isaac Newton
4. Thomas Edison

Q.

1 calorie = ___

1. 4.2 J

2. 42 J

3. 4.2 kJ

4. 42 kJ