Question 157: Laws of Motion

Question

A body of mass 2 kg slides down with an acceleration of 3 m/s
2
on a rough inclined plane having a slope of $${30^o}$$. The external force required to take the same body up the plane with the same acceleration will be : (g = 10 m/s
2
)

Accepted Answer

When mass slide down then,
Mgsin$$	heta $$ $$-$$ $$\mu $$Mg cos$$	heta $$ = Ma
$$ \Rightarrow $$ $$\,\,\,$$ a = g(sin30
o
$$-$$ $$\mu $$ cos30
o
)
When mass pushed upward with force F,
F $$-$$ Mgsin$$	heta $$ $$-$$ $$\mu $$ Mgcos$$	heta $$ = Ma
$$ \Rightarrow $$ $$\,\,\,$$ F = Mg(sin30
o
+ $$\mu $$ cos 30
o
) + Mg(sin30
o
$$-$$ $$\mu $$ cos30
o
)
$$ \Rightarrow $$ $$\,\,\,$$ F = 2Mg  sin30
o
= 2 $$ 	imes $$ 2 $$ 	imes $$ 10 $$ 	imes $$ $${1 \over 2}$$
= 20 N

Answer

14 N

Answer

20 N

Answer

6 N

Answer

4 N

Laws of Motion

A body of mass 2 kg slides down with an acceleration of 3 m/s 2 on a rough inclined plane having a slope of ${30^o}$. The external force required to take the same body up the plane with the same acceleration will be : (g = 10 m/s 2 )

Choose the correct answer: