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Physics - Mechanics?

by ZenithFaculty
Tags: mechanics, physics
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ZenithFaculty
#1
Sep26-06, 10:35 PM
P: 1
hey i got a problem

A snowball rolls off a barn roof that slopes downward at an angle of . The edge of the roof is 14.0 m above the ground, and the snowball has a speed of 7.00 m/s as it rolls off the roof. Ignore air resistance.


Part A
How far from the edge of the barn does the snowball strike the ground if it doesn't strike anything else while falling?

Part B
A man 1.9 m tall is standing 4.0 m from the edge of the barn. Will he be hit by the snowball?
I dont know how to get started a help would be great.
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Integral
#2
Sep27-06, 12:38 AM
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Integral's Avatar
P: 7,320
Solve this in 2 parts. First you have the falling body problem.

You need to find the component of the initial velocity which contributes to the falling motion. Use that to find the time the snowball takes to reach the ground. Once you know that time you can compute the distance from the barn.
Naumaan
#3
Sep27-06, 06:33 AM
P: 9
u havent mentioned the angle
anyhow
if let us suppose angle = @
the height of edge = y
and
the distance required = x
then
it is making a triangle having one side and one angle known
neglecting velocity
tan@ = y/x => x = y/tan@
from that u can find out the B part also
the solution is only mine
so if u feel i m wrong plz tell me .......
thanks

arunbg
#4
Sep27-06, 12:45 PM
P: 600
Physics - Mechanics?

Quote Quote by Naumann
u havent mentioned the angle
anyhow
if let us suppose angle = @
the height of edge = y
and
the distance required = x
then
it is making a triangle having one side and one angle known
neglecting velocity
tan@ = y/x => x = y/tan@
from that u can find out the B part also
the solution is only mine
so if u feel i m wrong plz tell me .......
thanks
No, this is not correct. You have forgotten to take inti account gravitational force in the motion. The path followed will be parabolic and not a straight line.
Follow Integral's advice.
For part B, you had better make an eqn in x and y for the projectile by eliminating time from the two eqns for x and y.Then put x value of the man in the obtained eqn, and see if the y value is greater than or less than the man's height.


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