Physics Help Please?

Question

A 34.0 kg seal at an amusement park slides down a ramp into the pool below. The top of the ramp is 1.55 m higher than the surface of the water and the ramp is inclined at an angle of 30.0° above the horizontal. The seal reaches the water with a speed of 4.90 m/s.

(a) What is the work is done by kinetic friction?

(b) What is the coefficient of kinetic friction between the seal and the ramp?

Neither my friend nor I can figure this one out. Any help will be very much appreciated. Thanks!!!

Answer 1

Work by motion W can be defined by the difference in potential energy Pe and final kinetic energy Ke.

W=Pe-Ke

W=mgh - (1/2)mV^2
W=m(gh - (1/2)V^2)

W=34( 9.81 x 1.55 - (1/2) (4.5)^2)=

W=173 Joules

b)Since W=fs
W=uNs
u - coefficient of friction
N- normal force
s- pass along which force was applied
N= mgcos(30)
s= h/sin(30)

so W=u mgcos(30) h/ sin(30)
W=umgh ctan(30)
finally
u= W tan(30)/(mgh)
u=173 tan(30) /( 34.0 x 9.81x1.55)=
u=.193

have fun

Answer 2

I am not going to give you the answer, but I will describe the method.

First calculate the velocity that the seal would reach the water with if there was no friction. The velocity should be more than 4.90 m/s. Then the kinetic energy at that velocity using 1/2 mv^2 can be calculated. Subtract the kinetic energy for the 4.90m/s from that number. This will give a value for the lost energy. The lost energy is due to frictional force which can be found by using E = F d , You know the E and d (distance down the slide) so now you can compute F the force. Then the coefficient of friction is computed as a ratio of this Force and the force of gravity normal to the surface of the slide on the seal.

Answer 3

Use the height above water to calculate the energy imparted to the seal by gravity. Then subtract the actual kinetic energy of the seal at impact.(1/2 MV^2). The difference is the work done by friction. The work done by friction equals the frictional force times the distance of the slide.Use trig to find the slide distance. The coefficient of friction equals the force of friction divided by the component of the seal's weight normal to the slide. That's how you do it. The rest is up to you.

Answer 4

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