Work Energy And Power Question 30
Question: Assertion : Soft steel can be made red hot by continued hammering on it, but hard steel cannot. Reason : Energy transfer in case of soft iron is large as in hard steel.
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: A
Solution:
The rise in temperature of the soft steel is an example of transferring energy into a system by work and having it appear as an increase in the internal energy of the system.
This works well for the soft steel because it is soft.
This softness results in a deformation of the steel under blow of the hammer.
Thus the point of application of the force is displaced by the hammer and positive work is done on the steel.
With the hard steel, less deformation occur, thus, there is less displacement of point of application of the force and less work done on the steel.
The soft steel is better in absorbing energy from the hammer by means of work and its temperature rises more rapidly.
