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A block rests on a rough inclined plane ...

A block rests on a rough inclined plane making an angle of `30 ^@` with the horizontal . The coefficient of static friction between the block and the plane is 0.8 If the frictional force on the block is 10 N the mass of the block is `" "(g=10 ms ^(-2))`

A

1 kg

B

2 kg

C

3 kg

D

4 kg

Text Solution

Verified by Experts

The correct Answer is:
B
Here , angle of inclination , `theta = 30^@`
Coefficient of static friction between block and plane `mu_s=0.8`
Frictional force on the block , f = 10 N
Let the mass of the block be m.
The various forces acting on the block are shown in the figure given here.

As the block is resting on the plane,
`:. f = mgsintheta`
or `m=f/(g sintheta)=(10N)/((10 " m s"^(-2))sin30^@)=2kg`
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Knowledge Check

  • A body of mass 2 kg rests on a rough inclined plane making an angle of 30^(@) with the horizontal. The coefficient of static friction between the block and the plane is 0.7. The frictional force on the block is :

    A
    9.8 N
    B
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    C
    `0.7 xx 9.8 N`
    D
    `0.7 xx 9.8 xx 3N`

  • A block kept on a rough surface starts sliding when the inclination of the surface is theta with respect to the horizontal . The coefficient of static friction between the block and the surface is

    A
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    B
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  • A block kept on a rough surface starts sliding when the inclination of the surface is 'theta' with respect to the horizontal. The coefficient of static friction between the block and the surface is :

    A
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