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Solved: CP Bang! A student sits atop a platform a distance
Chapter 3, Problem 74P(choose chapter or problem)
Problem 74P
CP Bang! A student sits atop a platform a distance h above the ground. He throws a large firecracker horizontally with a speed. However, a wind blowing parallel to the ground gives the firecracker a constant horizontal acceleration with magnitude a. As a result, the firecracker reaches the ground directly below the student. Determine the height h in terms of v, a, and g. Ignore the effect of air resistance on the vertical motion.
Questions & Answers
QUESTION:
Problem 74P
CP Bang! A student sits atop a platform a distance h above the ground. He throws a large firecracker horizontally with a speed. However, a wind blowing parallel to the ground gives the firecracker a constant horizontal acceleration with magnitude a. As a result, the firecracker reaches the ground directly below the student. Determine the height h in terms of v, a, and g. Ignore the effect of air resistance on the vertical motion.
ANSWER:
Solution 74P
The height is vertical motion,independent of horizontal motion except for time.first we have to horizontal motion
If the ball drops directly below the student,its average horizontal velocity will becomes zero,so in that time ball fell,the acceleration from wind will negated initial v,that is final v=-v.
Magnitude of change in velocity is 2v,
then
Now back to the vertical motion:
Using kinematics equation
Where u=0 and a=-g