2D kinematics -- Calculate the acceleration of the jumping athlete

AI Thread Summary
The discussion revolves around calculating the acceleration of a jumping athlete, initially leading to confusion over an answer of 11 m/s². The participant acknowledges making an error and seeks assistance in determining the direction of acceleration, specifically mentioning a "backward 55 degrees up" reactive force. Ultimately, they express satisfaction in resolving the initial calculation issue but still need to clarify the direction of acceleration. The conversation highlights the importance of considering all forces in kinematic calculations. Accurate direction determination is essential for complete understanding of the athlete's motion.
Stewkatt
Messages
6
Reaction score
3
Homework Statement
An athlete with a mass of 62 kg jumps and lands on his feet. The ground exerts a total force of 1.1 x 10^3 N [backward 55 degrees up] on his feet. Calculate the acceleration of the athlete
Relevant Equations
F=delta p/delta t =ma
DCD301E4-C8E1-43CD-A362-D64E05F31F14.jpeg

this is my work but the answers say 11 m/s^2 so I made an error somewhere. Also if someone could help me with solving the direction for the acceleration, that would be greatly appreciated.
 
Physics news on Phys.org
Perhaps because you have omitted the "backward 55 degrees up" direction of the reactive force.
 
image.jpg

yay, I figured it out. I still have to find the direction of acceleration and that’s it.
 
Stewkatt said:
yay, I figured it out. I still have to find the direction of acceleration and that’s it.
Did you find the direction of acceleration?
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top