- #1
cdubsean
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Homework Statement
A 4 kg steel ball strikes a wall with a speed
of 16 m/s at an angle of 50.6◦ with the normal
to the wall. It bounces off with the same
speed and angle, as shown in the figure.
http://img517.imageshack.us/img517/4498/physicspic1.png"
If the ball is in contact with the wall for
0.277 s, what is the magnitude of the average
force exerted on the ball by the wall?
Answer in units of N.
Homework Equations
Im = mvsin(8)i+mvcos(8)j
Fm= -mvsin(8)i+mvcos(8)j
Impulse = Fm - I am
Force average = Impulse/Time
8 = THeta
The Attempt at a Solution
Im = (4kg)(16m/s)(sin39.4) + (4kg)(16m/s)(cos39.4) = 90.078
Fm = -(4kg)(16m/s)(sin39.4) + (4kg)(16m/s)(cos39.4) = 8.832
Impulse = (8.832)-(90.078) = -81.246 Which I also found Impulse = -2(Mass)(Velocity)(Sin(8))
Then F adv= (-81.246)/ .227s = -357.912 N
This should be the case, but apparently I am wrong, can some one help me find my mistake, and I am aware I am useing a different angle than what is given, I am using the angle off the wall. So instead of 50.6 degrees, I am using 39.4 degrees. :) Help Plz.
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