Question

DUI
A block of mass 5 kg is pulled with a constant force of 25 N with the help of a string. The coefficient of friction
between the block and the ground is 0.2. Pulley is massless and string is massless and inextensible. When the
string makes an angle of 37° with the horizontal, the acceleration of the block is
A) 2 m/s
B) 4 m/s
C) 5m/s?
D) 2.6 m/s?​

Answer 1

Answer:

(D). 2.6 m/s²

Explanation:

The mass of the block = 5 kg

Force applied = 25 N

Angle of force = 37° with the horizontal.

Co-efficient of friction, μ = 0.2

Let us say the acceleration of the block is = a

So,

Normal force of the block can be given by,

$N=mg-25sin37\\N=5(9.8)-25(\frac{3}{5})=49-15\\N=34\,N$

Now,

Friction force can be given by,

$f=\mu N\\f=0.2(34)\\f=6.8\,N$

Now,

The acceleration of the block is given by,

$25.cos37-f=ma\\ma=20-6.8\\a=2.64\,m/s^{2}$

Therefore, the acceleration of the block is 2.6 m/s².

Hence, the correct option is (D).

Answer 2

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