Rollercoaster homework problem

[arrax]

Homework Statement

A roller-coaster car has a mass of 1150 kg when fully loaded with passengers. As the car passes over the top of a circular hill of radius 16 m, its speed is not changing. (a) At the top of the hill, what is the normal force (using the negative sign for the downward direction) FN on the car from the track if the car's speed is v = 8.5 m/s? (b) What is FN if v = 20 m/s?

m=1150kg
R=16m
v= 8.5 or 20

Homework Equations

a=v^2/R
F=m*[(v^2)/R]
-FN-mg=m[(-v^2)/R]

The Attempt at a Solution

Using the above equation I got b) correct with -17468.5 N. However, using the same equation with a) I get -6088.53 and it's incorrect. I don't know what I'm doing wrong.

Also, this is from Wiley Plus.

 

[ehild]

The Attempt at a Solution

Using the above equation I got b) correct with -17468.5 N. However, using the same equation with a) I get -6088.53 and it's incorrect. I don't know what I'm doing wrong.

Also, this is from Wiley Plus.

Check the sign of the force.

ehild

 

[arrax]

aside from a possible wrong sign, did you get a different number?

 

[ehild]

Think: can the track pull the roller coaster? What happens if upward force is needed to keep it on circular path?

ehild

 

[asteriatic]

As a scientist, it is important to carefully analyze and double check your calculations to ensure accuracy. In this case, it seems like there may be an error in your calculation for part (a). It may be helpful to break down the equation into smaller steps and double check each step to identify where the error may be occurring. Additionally, it may be beneficial to use a calculator or software program to help with the calculations and to avoid human error. It is also important to pay attention to units and make sure they are consistent throughout the calculation. If you are still having trouble, it may be helpful to seek assistance from a teacher or tutor. Remember, in science, accuracy is key, so it is important to carefully check your work to ensure the correct answer.