Question

A sled of mass m is given a kick on a frozen pond. The kick imparts to it an initial speed of 2.40 m/s. The coefficient of kinetic friction between sled and ice is 0.135. Use energy considerations to find the distance the sled moves before it stops.
m

Answer 1

m = mass of sled

w = weight of sled = mg

F_n = normal force on the sled = w = mg          since normal force balances the weight of sled

frictional force is given as

f = $\mu$ _k F_n = $\mu$ _k mg

V_i = initial speed = 2.40 m/s

V_f = final speed = 0 m/s

d = distance travel;led before stopping

using the work-kinetic energy theorem

- f d = (0.5) m (V_f² - V_i²)

- $\mu$ _k mgd = (0.5) m (0² - 2.40² )

- (0.135) (9.8) d = -2.88

d = 2.18 m