Question

Assertion: Machine parts are jammed in winter.
Reason: The viscosity of lubricant used in machine parts increase at low temperatures

• A. If both assertion and reason are true but the reason is the correct explanation of assertion.
• B. If both assertion and reason are true but the reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both the assertion and reason are false.
• E. If reason is true but assertion is false.

Answer 1

The correct option is A If both assertion and reason are true but the reason is the correct explanation of assertion.

Viscosity of a liquid decreases with increase in temperature and vice versa i.e,

$\eta =\frac{1}{\sqrt{T}}$

at low temperatures viscosity increases

Viscous drag increases

$F=-\eta A\frac{dv}{dx}$

force required to move the body or machine increases hence, machines are fammed