Kinematics in 2 dimensions, projectile velocity help

AI Thread Summary
The discussion revolves around two kinematics problems: the first involves calculating the time it takes for a javelin, launched at 34 m/s and 40° above the horizontal, to reduce its angle to 20°. The second problem questions the validity of a claim about Michael Jordan's jump duration of two seconds, prompting a calculation of the maximum height he could achieve. Participants emphasize the importance of showing one's work before seeking help, as assistance is typically provided only after effort is demonstrated. One user expresses frustration after calculating an implausible height of 19.6 m for Jordan's jump. Overall, the thread highlights the need for foundational understanding in solving projectile motion problems.
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Question 1-
In the javelin throw at a track-and-field event, the javelin is launched at a speed of 34 m/s at an angle of 40° above the horizontal. As the javelin travels upward, its velocity points above the horizontal at an angle that decreases as time passes. How much time is required for the angle to be reduced from 40° at launch to 20°?

Question 2-
Michael Jordan, formerly of the Chicago Bulls basketball team, has some fanatic fans. They claim that he is able to jump and remain in the air for two full seconds from launch to landing. Evaluate this claim by calculating the maximum height that such a jump would attain. For comparison, Jordan's maximum jump height has been estimated at about one meter.

IF ANYONE KNOWS HOW TO DO THIS...HELP WOULD BE GREATLY APPRETIATED
thanx
 
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i've been stuck on these problems for 5 hours now...and i need help

The second one is so tough...i mean i took into account the 2 seconds...and I'm getting 19.6 m as the answer...but that's not possible...
 
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Welcome to the Forums,

One is expected to show one's efforts before asking for help;

FAQ: Why Hasn't Anyone Answered my Question? - Moonbear said:
1) Did you show your work? Homework helpers will not assist with any questions until you've shown your own effort on the problem. Remember, we help with homework, we don't do your homework. We already passed those classes; it's your turn to do so.
 
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