- #1

bubblesarefun

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## Homework Statement

Crash Test Craig drives his 800kg car up a 100m ramp that is at an angle of 35 degrees above the horizontal. The car exerts a forward force of 12000N and the force of friction between the ramp and the car is 20N. He is trying to jump over a series of spinning helicopter blades that are each 8m across to reach another ramp down on the other side How many helicopter blades can he safely jump over?

Variables:

mass of car= 800 kg

distance or length of ramp= 100m

angle= 35 degrees

Applied(?) force= 12000N

Force of friction= 20N

Normal force= 9.8 m/s^2 * 800 kg = 7,840N

Force of gravity= 9.8 m/s^2 * 800kg = 7,840N

## Homework Equations

Vf^2=Vi^2 + 2ad

F=ma

There could be a variety of kinematics equations to use.

## The Attempt at a Solution

So, I thought since the car was exerting 12000N, that we could find the acceleration of the car using F=ma. I thought 12000N= 800kg*a and got a to be 15m/s^2. Then, assuming that initial velocity is 0 m/s, I solved for the final velocity using Vf^2= Vi^2 + 2ad. Vf^2= (0m/s)^2 + 2(15m/s^2)(100m). Vf= 54.77 m/s which is the launch velocity of the car as if leaves the ramp. I know I need to find the distance the car travels in the air and divide that by 8 to get the number of helicopter blades, but I am confused by what to do next.

Would final velocity be 0 m/s? Is acceleration 9.8 m/s^2? Is it now a vector problem? Do I use the force in any way?