Question

A substance of mass 100 kg is pulled over a floor.coefficients of static and kinetic friction are 0.5 and 0.45 respectively .find the force required to set the substance in motion and force required to set the substance in motion.

Answer 1

Given:

An object of mass 100 kg schooled on floor with coefficient of static friction 0.5 and coefficient of kinetic friction 0.45.

To find:

• Force to set the object in motion.
• Force to keep the object in uniform motion

Calculation:

Let force required to set the object in motion be f1:

$\sf{f1 = \mu_{s} \times normal \: reaction}$

$\sf{ = > f1 = \mu_{s} \times mg}$

$\sf{ = > f1 = 0.5 \times 100 \times 10}$

$\sf{ = > f1 = 500 \: N}$

Let force required to keep the object in uniform motion be f2:

$\sf{f2= \mu_{k} \times normal \: reaction}$

$\sf{ = > f2= \mu_{k} \times mg}$

$\sf{ = > f2= 0.45 \times 100 \times 10}$

$\sf{ = > f2 = 450 \: N}$

f2 is always a little less than f1 because the value of coefficient of kinetic friction is lesser than the coefficient of static friction