A hockey puck is hit on a frozen lake and starts moving with a speed of 12.0 m/s. Exactly 5.0 s later, its speed is 6.0 m/s. What is the puck’s average acceleration, and what is the coefficient of kinetic friction between puck and ice?

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Answer 1 · 2018-08-11T14:54:58

Average acceleration is #-"1.2 ms"^-2# and coefficient of frictional force is #0.12#

Average deceleration #(a_v)# is equal to change in velocity in given time.

So, #a_v =((12-6) \ "ms"^(-1))/"5 s" = 6/5 \ "ms"^-2#

Now, if this happened due to frictional force then we can say that the frictional force acting was

#f=muN=mumg#

where #mu# is coefficient of frictional force and #m# is its mass.

So, the deceleration caused by the force is

#f/m=mug#

And this is equal to #a_v#. So,

#a_v=mug#

Putting #g=9.8ms^-2#, we get

#mu=a/g=(6/5) \ "ms"^(-2)xx(1/(9.8 \ "ms"^(-2)))=0.12#