, where is the mass of the ball in kilograms.
Solution video
OpenStax College Physics, Chapter 8, Problem 20 (Problems & Exercises)
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Comments
Excuse me. Why is it cos(60) instead of sin(60), if you see the total impulse vertically?
Thanks for your question. At around 2:30 in the video we're finding the x-components of the two vectors to find the x-component of the resultant. Since the angles in the picture are with respect to horizontal, we use cosine to find the adjacent legs of the right triangles we imagine being created by each of these vectors.
For the final answer, wouldn't it be -20m/s(m) because you would multiply the 10 by 2?
Hi yusufkhan, thank you for the question. If the ball was moving directly towards the wall and bounced back with the same speed, then your answer of -20m/s(m) would be correct. However, in this question the ball is moving at an angle of above horizontal towards the wall. The component of momentum towards the wall is . is . It's this component that gets "multiplied by two", if you want to think of it that way, to get the end result of -10m/s(m). Hope this helps!
Shaun