Question

A contestant in a winter games event pushes a 50.0 kg block of ice across a frozen lake as shown in the figure below. The coefficient of static friction is 0.1 and the coefficient of kinetic friction is 0.03. (Assume θ = 30°.) (a) Calculate the minimum force F he must exert to get the block moving. 60.05 (b) What is its acceleration once it starts to move, if that force is maintained?

Answer 1

Normal force,

N = mg + F sin30

= 50*9.8+ F sin 30

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a)

Force needed to move the ice block

F cos x = uN = u( 50*9.8 + F sin 30)

where, F = applied force

x = angle (theta) = 30 deg

u = coefficient of static friction

F ( cos 30- 0.1sin 30)= 0.1*50*9.8

F= 60.05 N

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ma= F cos x - uk( mg + F sin 30)

uk = coefficient of kinetic friciton

50* a= 60.05* cos 30 - 0.03*( 50*9.8+ 0.1*60.05* sin 30)

a= 0.7444 m/s^2

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