A ) An ice skater is gliding horizontally across the ice with an initial velocit
ID: 1327299 • Letter: A
Question
A) An ice skater is gliding horizontally across the ice with an initial velocity of +6.02 m/s. The coefficient of kinetic friction between the ice and the skate blades is 0.0831, and air resistance is negligible. How much time elapses before her velocity is reduced to +2.51 m/s?
B)The parachute on a race car of weight 8260 N opens at the end of a quarter mile run when the car is traveling at 32.7 m/s. What total retarding force must be supplied by the parachute to stop the car in a distance of 1090 m?
Explanation / Answer
Retardation is written as
a = f/m
here, f is frictional force and equal to
f= kmg
therefore,the acceleration is
a = kg
a = 0.0831*9.81
= 0.8152 m/s^2
use the kinematic equation to calculate the time.
v = u - at
t = (u - v)/a
t = (6.02 -2.51)/( 0.8152 m/s^2)
=4.30 s
therefore, 4.30 s seconds are needed for retardation.
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