More frustrating force problems,

  • Thread starter Thread starter chimez14
  • Start date Start date
  • Tags Tags
    Force
AI Thread Summary
The discussion revolves around two physics problems involving force calculations. The first problem requires determining the normal force exerted on a chair being pushed at an angle on a frictional floor, emphasizing the importance of analyzing forces in the vertical direction. The second problem involves calculating the average force exerted by a man who falls and comes to rest after bending his knees, highlighting the need to consider the deceleration during the stopping distance. Participants suggest using free body diagrams to clarify the forces involved and recommend applying Newton's second law for both scenarios. Overall, the thread focuses on the application of fundamental physics concepts to solve force-related problems.
chimez14
Messages
6
Reaction score
0
More frustrating force problems, please help!

Homework Statement


1.)A chair of mass 10.1 kg is sitting on the horizontal floor; the floor is not frictionless. You push on the chair with a force of 47.7 N that is directed at an angle of 39.6 degrees below the horizontal and the chair slides along the floor. Calculate the normal force that the floor exerts on the chair

2.)A 87.7 kg man steps off a platform 2.89 m above the ground. He keeps his legs straight as he falls, but at the moment his feet touch the ground his knees begin to bend, and, treated as a particle, he moves an additional 0.60 m before coming to rest. Treating our rigid legged friend as a particle, what is the average force his feet exert on the ground while he slows down?

Note: Assume the acceleration while he is slowing down is constant


Homework Equations


For Question 1
u nid to find the sum of forces in the x and y directions respectively
for question 2
remember gravity


The Attempt at a Solution


i drew a free body diagram, i suggest u do d samem maybe there was a flaw in mine.
 
Physics news on Phys.org
For the first question, you don't really need to consider the forces in the x direction. What does your FBD look like for the y directions? This should be enough to sum up the forces.

For question 2 you need to consider the acceleration that's exerted on the person to make him stop in the given distance, and remember Newton's second law.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top