Finding the New Angle of Inclination: A Projectile Motion Problem

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The discussion centers on solving a projectile motion problem involving a ball launched from an inclined plane. Initially, the plane's inclination is 70 degrees, yielding a maximum range of 50 cm. When the inclination changes, the ball lands 1 meter away from the launcher, which is set at 30 degrees to the horizontal. The user attempts to calculate the new angle of inclination using a ratio derived from the maximum range and the given range, ultimately estimating the new angle to be approximately 30.3 degrees. The user expresses uncertainty about their approach and seeks validation or alternative methods for solving the problem.
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"Angle Of Inclination" problem

Homework Statement


A small ball is launched from the corner of an inclined plane. When the inclination of the plane α is 70deg the maximum range of the projectile is 50cm. Later, the inclination of the plane changes to new unknown angle, and the same projectile launcher is oriented at 30 deg to the horizontal line. The ball lands 1m away from the launcher on the inclined plane. Find the new angle of inclination.

Homework Equations


R = v2sin(2x) / g

The Attempt at a Solution



NB: For those of you who haven't heard of this, you attached a ball launcher to the corner of a piece of wide wood (or other solid material), and you incline said solid material at different angles. As you go down, the ball travels further horizontally on the plane. It had something to do with altering g at different angles of inclination

For the first situation, I know that the degree of the launcher was 45o, since we're referring to maximum range.

For the second situation, I had the idea of doing sin(2*45) / sin(2*30) = 1.1547. This might be totally wrong, but my "idea" at the time was that I could find the ratio with which the max. range was greater than the given range (if that makes any sense)

Since 1.1547 * 1 = 1.1547, I can do 1.1547 / 0.5 = 2.3094, giving me the ratio of the new angle of inclination to the old one.
Henceforth, 70 / 2.3094 = 30.3 degrees (approximately)

Honestly, did I approach this problem in the right way at all? I feel like that I did something horribly wrong when trying to solve it...
 
Last edited:
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Bump...
 


Bump again.

Seriously, has nobody else found an alternate way to approach this problem?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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