Work Power Energy Question 3
Question 3 - 2024 (29 Jan Shift 1)
A block of mass $100 \mathrm{~kg}$ slides over a distance of $10 \mathrm{~m}$ on a horizontal surface. If the co-efficient of friction between the surfaces is 0.4 , then the work done against friction (in $\mathrm{J}$ ) is :
(1) 4200
(2) 3900
(3) 4000
(4) 4500
Show Answer
Answer: (3)
Solution:
Given $\mathrm{m}=100 \mathrm{~kg}$
$\mathrm{s}=10 \mathrm{~m}$
$\mu=0.4$
As $\mathrm{f}=\mu \mathrm{mg}=0.4 \times 100 \times 10=400 \mathrm{~N}$
Now $\mathrm{W}=\mathrm{f} . \mathrm{s}=400 \times 10=4000 \mathrm{~J}$
