# Force on a hot wheel car lab

1. Jan 2, 2009

### pamelaislost

How would you find fnet if there is no force applied?
does anything happen to the other forces as well?

how do you find the theoretical and actual distances traveled up and down an incline if you have photogate data and need to find the theoretical and actual distance traveled?
should i have measured the distance by hand when i set up the experiment?

2. Jan 5, 2009

### chrisk

Given the information you provided, the following is assumed: frictionless surface and wheel bearings, and no air resistance. Then this is a conservation of energy problem. Initially, the car is at an initial height h0 above the lowest point of the track with an initial velocity of zero. So the stored energy (potential energy) is m*g*h0 where m is the mass of the car, and g is the acceleration of gravity, and the initial kinetic energy is zero (v = 0). When the car is released, the potential energy is converted into kinetic energy, KE = 1/2mv^2. The sum of the potential energy and kinetic energy must always equal the initial energy, m*g*h0. Therefore, the velocity of the car is only a function of the height. When the car is at the lowest point on the track, all the potential energy has been converted to kinetic energy i.e. m*g*h0 = 1/2mv^2 and solve for v. This is the maximum velocity of the car. Velocity calculations at any height will show that v is independent of the mass of the car so the mass does not need to be measured. Please clarify the forces you are trying to calculate. Is it the normal force while the car is in a 360 degree loop? The mass of the car will be needed for force calculations.