Categories: Ask Physics, Feynmann, HC VERMA Tags:
Force – Impulse – Momentum
Hi All! I’m having mega problems with one part of a physics assignment. Looking for any help.
The details are as follows:
The diagram shows the normal force on Christine’s feet vs. time, as recorded by a force plate while she stands still initially (until point B), then jumps off the plate. (This trial is separate from the one in the previous problem. The graph is over-simplified and idealised, compared to reality.) When her feet leave the plate, the normal force is zero.
1)What is the magnitude of the (upward) impulse generated by the normal force of Christine during the time interval of her jump off the plate?
2)What is the magnitude of the downward impulse due to gravity during this interval?
3)What is the net impulse which propels her upwards when she jumps off the plate? (Recall, the net force on her is the normal force minus the force of gravity.)
4)What is her change in speed upwards for this process?
The graph has NORMAL FORCE (N) on the y-axis and TIME (s) on the X axis.
The line is at a constant 550 N until point B (1.75 seconds) at which time it shoot up vertically to 1550 N at a time of 1.95 seconds. It peaks at this time and position then drops down to 0 N at 2.15 seconds.
Thanks in advance for any guidance that can be provided!
… Sara
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Understanding Projectile Motion
IN A PROJECTILE MOTION WE TAKE MOTION IN A HORIZONTAL DIRECTION AS g=0 while in vertical motion as g=-9.8 meter / second square why?
Asks Atanu PAUL
Projectile Motion is an example for motion in two dimension. It can be studied easily by resolving into two components – The vertical motion is affected by gravity and the horizontal motion is not affected by gravity.
Therefore we take g=0 when we consider the horizontal component of motion as the projectile is not accelerated in the horizontal direction. The horizontal component of velocity remains constant through out its motion.
The following presentation will help you understand the concept better.
A PowerPoint Presentation on projectile_motion
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