Arescue worker pulls an injured skier lying on a toboggan (with a combined mass of 127 kg) across flat snow at a constant speed. a 2.43 m rope is attached to the toboggan at ground level, and the rescuer holds the rope taut at shoulder level. if the rescuer's shoulders are 1.65 m above the ground, and the tension in the rope is 148 n, what is the coefficient of kinetic friction between the toboggan and the snow?

0.088

Explanation:

from the question we are given the following

combined mass (m) = 127 kg

acceleration (a) = 0  (because speed is constant)

length of the rope = 2.43 m

height of the rescuers shoulder = 1.65 m

tension in the rope (T) = 148 N

acceleration due to gravity (g) = 9.8 m/s^2

coefficient of kinetic friction (μ) = ?

firstly from the diagram attached we can see that the rope and the rescuer with the ground for a right angled triangle with the rescuer being the opposite side and the rope being the hypotenuse. We can calculate the angle (θ) between the rope and the ground using the formula

sin θ = opposite / hypotenuse

θ = sin^(-1)   x   (opposite / hypotenuse ) =  sin^(-1)   x   (1.65 / 2.43 )

θ = 42.8 degrees

we can get the coefficient of kinetic friction by applying the formula below

net force = force  by the rescuer - force of kinetic friction (force as a result of kinematic friction)  .....equation 1

where

        force of kinetic friction = (( 127 x 9.8 ) - ( 148 x sin 42.8)) x  μ

        force of kinetic friction = (1244.6 - 100.6) x μ = 1144μ

now substituting all the values in to equation 1 we have

0 =100.49 - 1144μ

1144μ = 100.49

μ = 0.088

i would like to make dinner for my mom, dad, and sister

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s