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4-2.Friction
easy
An object of mass $1 \,kg$ moving on a horizontal surface with initial velocity $8 \,m / s$ comes to rest after $10 \,s$. If one wants to keep the object moving on the same surface with velocity $8 \,m / s$ the force required is ...... $N$
A$0.4$
B$0.8$
C$1.2$
DZero
Solution
(b)
To find the frictional force offered by the ground
$v=u+a t$
$v=0$
$0=8-\mu g(10)$
$\mu=\frac{8}{100}=0.08$
To move the body with constant velocity on this surface, internal force applied should be equal to friction force $F=\mu m g$
$=(0.08)(1)(10)=0.8\,N$
To find the frictional force offered by the ground
$v=u+a t$
$v=0$
$0=8-\mu g(10)$
$\mu=\frac{8}{100}=0.08$
To move the body with constant velocity on this surface, internal force applied should be equal to friction force $F=\mu m g$
$=(0.08)(1)(10)=0.8\,N$
Standard 11
Physics
