Two balls of masses ${m_1}$ and ${m_2}$ are separated from each other by a powder charge placed between them. The whole system is at rest on the ground. Suddenly the powder charge explodes and masses are pushed apart. The mass ${m_1}$ travels a distance ${s_1}$ and stops. If the coefficients of friction between the balls and ground are same, the mass ${m_2}$ stops after travelling the distance
${s_2} = \frac{{{m_1}}}{{{m_2}}}{s_1}$
${s_2} = \frac{{{m_2}}}{{{m_1}}}{s_1}$
${s_2} = \frac{{m_1^2}}{{m_2^2}}{s_1}$
${s_2} = \frac{{m_2^2}}{{m_1^2}}{s_1}$
When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that it acts
A $\vec F\,\, = \,\,\hat i\, + \,4\hat j\,$ acts on block shown. The force of friction acting on the block is :
An isolated rail car originally moving with speed $v_0$ on a straight, frictionles, level track contains a large amount of sand. $A$ release valve on the bottom of the car malfunctions, and sand begins to pour out straight down relative to the rail car. What happens to the speed of the rail car as the sand pours out?
A $20\, kg$ block is initially at rest on a rough horizontal surface. A horizontal force of $75 \,N$ is required to set the block in motion. After it is in motion, a horizontal force of $60\, N$ is required to keep the block moving with constant speed. The coefficient of static friction is
As shown in the figure a block of mass $10\,kg$ lying on a horizontal surface is pulled by a force $F$ acting at an angle $30^{\circ}$, with horizontal. For $\mu_{ s }=0.25$, the block will just start to move for the value of $F..........\,N$ : $\left[\right.$ Given $\left.g =10\,ms ^{-2}\right]$