Finding speed -- A child on his toboggan

[Jeanclaud]

Homework Statement

A child on his toboggan is pulled by his father with a force F of value F=240N,on a ice track making an angle α=30° With the horizontal.the cord that the father is holding makes an angle β=20° With the track.assuming that the system(child,toboggan) has a mass of M=40Kg and is moving with a constant velocity, take g=10m/s^2
1.determine the acceleration of the system
2.determine the value of force of friction
3.determine the value of normal reaction of the plane on the system.
4. Find the speed of the child after covering a distance of 5m.

Homework Equations

ΣFext=ma
Vf^2-Vi^2=2ad

The Attempt at a Solution

1.a=0m/s^2
2.Fr=25.52N
3.N=264.32N
My problem was with part 4 if a=0 so it is type of motion is URM how should I get the speed without knowing the time?

 

[gneill]

How much does speed change over time if acceleration is zero? I mean, this presumes that the father doesn't let go of the cord...

 

[Jeanclaud]

How much does speed change over time if acceleration is zero? I mean, this presumes that the father doesn't let go of the cord...

He didn't let go of the cord, I didn't mention that.