A 25 kg child is sitting on a 10 kg sled. The child’s older sister is pulling the sled horizontally across the snow at a constant speed of 4 m/s by pulling on a rope with a force of 25 N at an angle of 30o above the horizontal.

Question

A 25 kg child is sitting on a 10 kg sled.  The child’s older sister is pulling the sled horizontally across the snow at a constant speed of 4 m/s by pulling on a rope with a force of 25 N at an angle of 30o above the horizontal.

[4]    a.    Draw all appropriate diagrams for the situation.

[3]    b.    Find the normal force acting on the sled.

[3]    c.    Find the magnitude of the force of friction between the sled and the snow.

Anonymous · Answer

m =35 kg
m g = 35 * 9.81 = 343 Newtons weight
force up from tow line = 25 sin 30 = 12.5 N up
net contact force with snow = 343 - 12.5 = 331 N
speed constant so friction force = horizontal component of friction force
= 25 cos 30 = 21.7 Newtons

Anonymous · Answer

TYPO: speed constant so friction force = horizontal component of tow line force