Question

A soccer ball is kicked at an angle of 30 degrees with the horizontal. Which of the following best describes what happens to the horizontal velocity of the ball as it flies through the air?

Also, A soccer ball is kicked at an angle of 30 degrees with the horizontal. Which of the following best describes what happens to the vertical velocity of the ball as it flies through the air?

a. it increases
b. it decreases
c. it increases, then decreases
d. it decreases, then increases
e. it remains the same

Answer 1

C. It increases, then decreases?

Answer 2

That would be the assumed answer, but no that is not correct.

Answer 3

so have you ever thrown a ball upwards?

Answer 4

or actually seen anyone throw a ball upwards? can you describe how it moves?

Answer 5

sorry I just realized that might sound a bit condescending/sarcastic (but honestly I don't mean it in that way :) ). But if you look at the motion of a ball being thrown upwards (and I mean a ball being thrown directly upward as hard as that person can) you can see that the ball when it leaves the fingers of the person is really fast but when it reaches it's peak it's really slow. Therefore we can actually see the ball slowing down.

To put in a physics/mathematical way: After leaving the fingers, the ball only has one force acting upon it aka GRAVITY. Now gravitational force is always pointing down. Since the force is in the exact opposite direction as the velocity (aka direction that you are moving in). The velocity magnitude decreases.

Does this all make sense?

Answer 6

So in other words, it is D., It decreases, then increases?

Answer 7

yup! And the physic explanation for the increase, is that at the peak the velocity changes direction now, right? It's now pointing in the same direction as the gravitational force. Thusly, the velocity increases. Most people call this "accelerating" however in the physics world while something increasing velocity is accelerating so is something decreasing velocity.