Question

Imagine throwing a ball vertically up into the air.


What is the motion of the ball like while it is moving upward, after it has left your hand
but before it reaches its maximum height? You can ignore friction and air resistance.

Answer 1

A. The ball is speeding up
B. The ball is slowing down
C. The ball is moving at a constant speed

Answer 2

Why hello there again lol.

Answer 3

Hi! @1DEA :) so i know that when friction/air resistance is present that the ball is slowing down because it is moving in the opposite direction of motion, but is that the same for when air resistance and friction is negligible?

Answer 4

haha kind of. So actually, the ball is not really slowing down because of friction and air resistance (it is but to a very small degree, smallest enough that most questions will ask you to ignore them). It is really is slowing down due to the force of gravity. Does this make sense?

Answer 5

ahhh yes! i remember learning about that now! so it would be B. The ball is slowing down and its because of the force of gravity and its going against that force?

Answer 6

exactly! which is why it accelerate when it comes down...(this is extra) until a certain point, called the terminal velocity which is result of air resistance called drag.

Answer 7

awesome! thanks :D

Answer 8

so then this question: While the ball is moving upward, are the forces acting on it balanced or unbalanced?
Are they in the direction of motion or opposite to the direction of motion?

Answer 9

it would be balanced and in the opposite direction of motion right?

Answer 10

i mean unbalanced!

Answer 11

yes exactly, I was just about to ask you what balanced forces mean

Answer 12

so it is unbalanced because theres a change in speed and in this case what force would be greater?

Answer 13

so forces cause acceleration, and acceleration causes a change in velocity (you can called this speed, but as I'm sure you know speed is just the magnitude of velocity). If the net force is in the same direction as your motion will speed up, and it is true vice versa.

Answer 14

okay thanks :)

Answer 15

so what force is greater?

Answer 16

gravity would be the greater force correct?

Answer 17

Yes! And actually if you think about it, it is the ONLY force acting on the ball!

Answer 18

thats exactly what i was thinking!

Answer 19

Imagine a ball falling vertically down from the fourth floor of a building.

What is the motion of the ball like while it is moving downward, after it has left your hand but before it reaches the ground? You can ignore friction and air resistance.

Answer 20

you got this!

Answer 21

A. the ball is slowing down
B. the ball moves at a constant speed
C. the bal is speeding up

Answer 22

the only thing throwing me off is vertical but thats just basically saying throwing a ball down right?

Answer 23

so then the ball would be speeding up?

Answer 24

then the forces would be unbalanced and IN the direction of motion?!

Answer 25

well we are not throwing the ball down, we are just letting it go but YES! you are correct! AND YES!!! that is it exactly!

Answer 26

YAY! :D just one more! Im just confused because it has to do with GPE which I'm not too confident about and I know that height and mass are two factors, but I don't think the height would matter in this case only the mass right ?

Answer 27

Consider a ball sitting on a tabletop, about to fall on the ground. Just before the ball rolls
off the table, it has gravitational potential energy (GPE). The amount of GPE the ball has depends on which of the following?

Answer 28

A. Only the ball’s mass and the speed with which the ball rolls off the table
B. The height of the table
C. The speed with which the ball rolls off the table
D. Only the ball’s mass and the height of the table
E. All of these
F. The ball’s mass

Answer 29

so let me first give you the formula for GPE:
\[GPE = mgh\]
where m = mass, g = graviational constant, h = height

Answer 30

okay so that shows that both mass and height are important, so I'm thinking it would be D!

Answer 31

DING DING DING 100% correct!

Answer 32

YAY! OMG Thank you sooooo much!

Answer 33

no problem but physics is not so bad right? In fact it elementary! lol.

Answer 34

yeah! it just seems really intimidating and being an english major seeing math and science just scares me! lol

Answer 35

Ooh nice college. eh? what college if you don't mind me asking?

Answer 36

UT!

Answer 37

Ohhh nice, that's soooo far from me though lol! But don't worry about being intimidated! I being a former science major can tell you that while numbers and scientific processes might scare you english majors, literature and art scares us science majors!

Answer 38

haha! thats hilarious! well good luck to you and thank you SO much for the help:)

Answer 39

no problem anytime!