Calculating Force of Friction on a Bicyclist

[ViewtifulBeau]

with a terminal speed of 0.2 mm/s. The particle has a mass of 10^-10 g and a retarding force of the form bv. What is the value of b? i converted everything to SI and i got -4.905e-08 kg/s but it is wrong.. am i close?

another question...

A bicyclist travels in a circle of radius 26 m at a constant speed of 7.44 m/s. The combined mass of the bicycle and rider is 95 kg.

The force of friction exerted on the bike from the road is 202 N but i need to find the total force exerted by the road on the bike. I thought it would be 202 + mg (normal force) which would be 1130. but that is not right. then i tried just normal force so i did 95 * 9.81 and i got 932. and that is wrong too!

 

[StNowhere]

2nd part: I may be wrong here, but because force is a vector quantity, and since the normal force and friction do not act in the same direction, you cannot simply add to find the total force.

 

[quicknote]

For the first question, your calculation for the value of b is incorrect. To find the value of b, you need to use the equation F = bv, where F is the retarding force, b is the coefficient of friction, and v is the velocity. Rearranging the equation, we get b = F/v. Plugging in the values, we get b = 202/0.2 = 1010 kg/s. This is the value of b.

For the second question, you are on the right track. The total force exerted by the road on the bike is equal to the force of friction plus the normal force. So, the correct equation would be Ftotal = Ffriction + mg. Plugging in the values, we get Ftotal = 202 + (95*9.81) = 1090 N. This is the total force exerted by the road on the bike. Your first attempt of adding the normal force to the force of friction was correct, but you made a mistake in your calculation. Your second attempt of only considering the normal force was incorrect, as it does not take into account the force of friction that is acting on the bike.