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A block of mass m = 4 Kg  is given an initial velocity v = 20 m/s 

up to the plane as shown in the figure . find the work done by frictional force \mu = 0.5  and g = 10 m/s 

before the block stop for a while 

Option: 1 100

Option: 2 -100

Option: 3 -320

Option: 4 -350

Answers (1)

best_answer

As we have learned

Work done by the frictional force is negative, when the force is large enough to overcome the friction

g_{net } = g \sin \theta + \mu g \cos \theta  

g _{net } = 10 \times \frac{3}{5} + 0.5 \times 10 \times \frac{4}{5}

Now 

 

v^2 = u^2 - 2as \\ for\: \: v = 0 \: \: \: u^2 =2as \: \: or \: \: s = \frac{u^2}{2g_{net}}=\frac{20*20}{2*10}=20

S = 20 m

W_f_0 = 16 \times 20 \times (-1 ) = -320 J

 

 

 

 

 

 

Posted by

Shailly goel

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