physics
posted by alexa on .
I have a question based off of the response to the question I posted below.
A dragster and driver together have mass 918.8 kg. The dragster,starting from rest,attains a speed of 25.8 m/s in .53s .
Find the average acceleration of the dragsters during this time interval. Answer in units of m/s^2.
Assume the driver has a mass of 73.6kg. What horizontal force does the seat exert on the driver?
my question about henry's response is: IS THE HORIZONTAL FORCE ZERO OR 721.3N?
(this is henry's response:
a = 25.8 / 53 = 0.487m/s
F = 918.8*0.487 = 447.5N.
Fd = mg = 73.6kg * 9.8N/kg = 721.3N.
The angle between seat and hor = 0 deg.
Fh = 721.3sin(0) = 0 Newtons.
Fv = 721.3cos(0) = 721.3N = ver. force of driver.)
MY QUESTION IS:Is the horizontal force zero N? or is it 721.3N?

the horizontal force is the mass of the driver times the horizontal acceleration
F = m a
F = 73.6 * .487 = 35.84 Newtons
The horizontal force has nothing to do with g, which is in the vertical direction. It also has nothing to do with the mass of the car. That has to do with the force the road exerts on the tires. 
Accelerationa=velocity(v)/time taken(t).we kwn dat speed(S)=velocity.a=25.8/53=0.49ms2