A skateboarder is trying to take a sharp turn (radius of 1.2m). She grabs hold of a tree branch to help make the turn. She pulls with 45 N of force. If she makes the turn going 3.2 m/s, what is the coefficient of friction between the wheels and ground. The mass of the girl and board together is 35 kg. Identify the F net equation and coefficient of friction value that best fits the above situation.

Explanation:

The skateboarder moves on a circular path of radius 1.2 m with velocity 3.2 m /s so centripetal force required

= m v² / r , m is mass , v is velocity and r is radius of the circular path.

= 35  x 3.2² / 1.2

= 298.67 N

Force 45 N is provided by tree branch . The rest will be provided by frictional force

frictional force F  = 298.67 - 45

= 253.67 N

weight = reaction force of ground = 35 x 9.8

= 343 N

Coefficient of friction = friction / reaction force

= 253.67 / 343

= .74 .

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min