4

As The Photon wrote in a comment, the issue is that you have to accelerate your hand as well. So while the 4.4g bullet only needs 304N to accelerate (by your numbers in the comments), your 400g hand has to reach the same speeds on roughly the same distances, requiring on the order of 30000N, well outside the range of the human body. You may, however, be ...


3

In general, the effects of air resistance are rather complicated, and not all that accessible to high-school students except in a quantitative way. But here's a brief run-down of how air resistance works and how it affects the solutions of the equations of motion. For most everyday situations, the drag force from a fluid can be modeled in one of two ways: ...


2

The problem is simply that we can't move our arms quickly enough. We have the strength- a lever-action airgun shows that the equivalent of a good shove is enough to fire a pellet- but we don't have the speed.


2

In your solution to the problem, you have not clearly defined what you mean by $\theta$ and as a result you might have confused yourself: in your solution, $\theta$ is the angle that the velocity makes with the horizontal axis at point $H$, ie the point where the height is at half its maximum. Furthermore, this point is when the particle is going downwards ...


2

Another way of attacking this problem: The vertical motion is symmetric with respect to time about the high point. The last second of rising is a mirror image of the first second of falling. If you happen to notice the ball just as it reaches the high point and starts to fall back, how far will it fall from rest in one second? How fast must you throw the ...


1

mg is the force that the earth does on the ball, it is not the force between the head and the ball. This last force will be a function of the contact speed when they collide


1

Supposing that the propellant for the bullet is not affected by the different environment, the bullet will accelerate slightly faster due to the (much) thinner atmosphere. There is no other difference up to the gun's muzzle. Beyond that, the bullet will decelerate slower, due to both lower gravitational acceleration and thin atmosphere. The maximum height ...


1

There are so few gas molecules in (orbital) space that the space shuttle was not frictionally heated by them. Instead, the shuttle was heated primarily by the sun's rays.


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