Rocky launcher

Classical Mechanics Level 1

Becky is trying to throw a $1\text{ kg}$ rock as far as possible. She threw the rock 4 times, at an angle of $20 ^ \circ, 40 ^ \circ, 60 ^ \circ$ and $80 ^ \circ$ with respect to the horizontal. Which of those resulted in the rock traveling the furtherest horizontally?

Details and Assumptions

The rock completely stops motion on its first contact with the ground.
Ignore any air resistance.

80^\circ

20^\circ

60^\circ

40^\circ

3 solutions

Tom McDonald
Jul 17, 2015

45 degrees is the optimum angle as it gives the best compromise between a large vertical component of the force (extending time of flight) and a large horizontal component (increasing distance travelled).

40 degrees is the closest to 45 degrees making it the correct answer.

Also, the difference (-5°) can be attributed to the fact that she threw the projectile from some initial height.

Daren Lobo - 5 years, 11 months ago

I don't think that would make a difference because the range is not mentioned here. So if we have to throw anything as far as possible then 45 degrees is the best angle. If she threw it from some initial height at an angle of 45 then only it would cover the maximum possible distance.

Rishabh Tripathi - 5 years, 11 months ago

Potsawee Manakul
Jul 18, 2015

$S_{x}=\frac{u^2\sin2\theta}{g}$ Therefore, $S_{x}\propto \sin2\theta$ It can be seen that at 40 degrees, it will move for the farthest distance (compared to other angles given in this problem)

Arnab Mukherjee
Jul 26, 2015

For best results,it should be thrown at an angle if 45. But as it is not in the option,40 is the correct ans.

Rocky launcher

3 solutions

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