A block of 7 kg is placed on a rough horizontal surface and is pulled through a variable force F (in N ) = 5 t , where t is time in second, at an angle of 3 7 ∘ with the horizontal. The coefficient of

Question

A block of 7 kg is placed on a rough horizontal surface and is pulled through a variable force F (in N ) $= 5 t$ , where $t$ is time in second, at an angle of $3 7^{\circ}$ with the horizontal. The coefficient of static friction of the block with the surface is one. If the force starts acting at $t = 0 s$ , if the time (in sec) at which the block starts to slide is found to be 10 n . Find the value of n . (Take $g = 10 m / s^{2}$ )

Answer:

1

Solution:

$F cos 3 7^{\circ} = μ (m g - F sin 3 7^{\circ})$

$5 t [cos 3 7^{\circ} + μ sin 3 7^{\circ}] = μ mg$

$5 t [\frac{4}{5} + \frac{3}{5}] = 70$

$t = 10 seco n d$

TestHub · Accepted Answer

F cos 3 7 ∘ = μ ( m g − F sin 3 7 ∘ ) 5 t [ cos 3 7 ∘ + μ sin 3 7 ∘ ] = μ mg 5 t [ 5 4 ​ + 5 3 ​ ] = 70 t = 10 seco n d

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