There are two inclined surfaces of equal length $(L)$ and same angle of inclination $45^{\circ}$ with the horizontal. One of them is rough and the other is perfectly smooth. A given body takes 2 times as much time to slide down on rough surface than on the smooth surface. The coefficient of kinetic friction $\left(\mu_k\right)$ between the object and the rough surface is close to
A box of mass $$5 \mathrm{~kg}$$ is pulled by a cord, up along a frictionless plane inclined at $$30^{\circ}$$ with the horizontal. The tension in the cord is $$30 \mathrm{~N}$$. The acceleration of the box is (Take $$g=10 \mathrm{~m} \mathrm{~s}^{-2}$$)
A horizontal force $$10 \mathrm{~N}$$ is applied to a block $$A$$ as shown in figure. The mass of blocks $$A$$ and $$B$$ are $$2 \mathrm{~kg}$$ and 3 $$\mathrm{kg}$$ respectively. The blocks slide over a frictionless surface. The force exerted by block $$A$$ on block $$B$$ is :
A particle moving with uniform speed in a circular path maintains:
A block of mass 2 kg is placed on inclined rough surface AC (as shown in figure) of coefficient of friction $$\mu$$. If g = 10 m s$$^{-2}$$, the net force (in N) on the block will be:
A football player is moving southward and suddenly turns eastward with the same speed to avoid an opponent. The force that acts on the player while turning is :
Calculate the maximum acceleration of a moving car so that a body lying on the floor of the car remains stationary. The coefficient of static friction between the body and the floor is 0.15
$$\left(g=10 \mathrm{~m} \mathrm{~s}^{-2}\right)$$.
A bullet from a gun is fired on a rectangular wooden block with velocity $$u$$. When bullet travels $$24 \mathrm{~cm}$$ through the block along its length horizontally, velocity of bullet becomes $$\frac{u}{3}$$. Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is :
If $$\overrightarrow F = 2\widehat i + \widehat j - \widehat k$$ and $$\overrightarrow r = 3\widehat i + 2\widehat j - 2\widehat k$$, then the scalar and vector products of $$\overrightarrow F $$ and $$\overrightarrow r $$ have the magnitudes respectively as
In the diagram shown, the normal reaction force between 2 kg and 1 kg is (Consider the surface, to be smooth) :
(Given g = 10 ms$$-$$2)




The coefficients of static and kinetic friction between the box and the plank will be, respectively



The coefficient of static friction between the block and the cart is $$\mu $$. The acceleration $$\alpha $$ of the cart that will prevent the block from falling satisfies


Three forces acting on a body are shown in the figure. To have the resultant force only along the y-direction, the magnitude of the minimum additional force needed is



