Can you check my solving?


by AvrGang
Tags: check, solving
AvrGang
AvrGang is offline
#1
Sep28-07, 11:15 AM
P: 28
1. The problem statement, all variables and given/known data

A stunt man drives a car at a speed of 20 m/s off a 30-m-high cliff.
The road leading to the cliff is inclined upward at an angle of 20(degrees).
a. How far from the base of the cliff does the car land?
b. What is the car's impact speed?

2. Relevant equations



3. The attempt at a solution

Here is my solving:

Vix=Vicos@
=20cos20
=18.8m/s

Viy=Visin@
=20sin20
=6.84m/s

a) How far from the base of the cliff does the car land?
x=Vix t
x=18.8t ------(1)

y=Viy t - 1/2gt^2
-30=6.84t-0.5(9.8)t^2
-4.9t^2+6.84t+30=0 (divide this by -4.9)
t^2-1.39t+30=0
From this equation we can find t then sustitute its magnitude in equation 1, so we can find x

b)speed=sqrt((Vfx)^2+(Vfy)^2)
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AvrGang
AvrGang is offline
#2
Sep28-07, 11:17 AM
P: 28
sqrt is square root


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