Laws of Motion

Question : 25

Total: 40

Figure shows a man standing stationary with respect to a horizontal conveyor belt that is accelerating with 1 m s‌–2. What is the net force on the man? If the coefficient of static friction between the man’s shoes and the belt is 0.2, up to what acceleration of the belt can the man continue to be stationary relative to the belt? (Mass of the man = 65 kg)

Solution:

Here, acceleration of conveyor belt, a=1ms–2
As the man is standing stationary w.r.t. the belt, so acceleration of the man = acceleration of belt a=1m s–2
As m=65kg
∴ Net force on the man, F=ma=65×1=65N
Now µ=0.2
Force of limiting friction; f=µR=µmg
If the man remains stationary upto maximum acceleration a′ of the belt, then
f=ma′=µmg,
a′=mg=0.2×10=2ms–2

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