JEE Advance - Physics (2008 - Paper 2 Offline - No. 11)

STATEMENT 1 : It is easier to pull a heavy object than to push it on a level ground.

and

STATEMENT 2 : The magnitude of frictional force depends on the nature of the two surfaces in contact.

Statement 1 is True, Statement 2 is True; Statement 2 is a CORRECT explanation for Statement 1

Statement 1 is True, Statement 2 is True; Statement 2 is a NOT CORRECT explanation for Statement 1

Statement 1 is True, Statement 2 is False

Statement 1 is False, Statement 2 is True

Case I : Free body diagram.

IIT-JEE 2008 Paper 2 Offline Physics - Laws of Motion Question 5 English Explanation 1

Frictional force ($$fr$$) = $$\mu$$N

Normal force (N) = N$$_1$$ + $$mg$$

Frictional force ($$fr$$)$$_\mathrm{I}$$ = $$\mu$$(N$$_1$$ + $$mg$$) ..... (i)

Where N = Normal force

$$\mu$$ = Coefficient of friction

$$m$$ = mass of object

$$g$$ = acc. due to gravity

N$$_1$$ = Normal force i.e., vertical component of force due to push.

N$$_2$$ = Parallel component of force due to push.

Case II : Free body diagram (Pull)

IIT-JEE 2008 Paper 2 Offline Physics - Laws of Motion Question 5 English Explanation 2

For balancing the force,

N = N$$_1$$ $$-$$ $$mg$$

Frictional force $$(fr)$$$$_\mathrm{II}$$ = $$\mu$$N ..... (ii)

From eq. (i) and (ii)

$$(fr)$$$$_\mathrm{I}$$ > $$(fr)$$$$_\mathrm{II}$$

In case of pull, it is easy to move object.

Statement 1 is true. Statement 2 is true.

IIT-JEE 2008 Paper 2 Offline Physics - Laws of Motion Question 5 English Explanation 3

Force of friction depends on roughness of two surfaces in contact. If roughness will increase, the force of friction will also increase.