Question

I need to create a problem where someone is pole vaulting and one of the first things I'm trying to calculate is projectile motion. please help! i already made up a problem but I'm not sure how to do projectile motion

Answer 1

are you familiar with vectors?

Answer 2

yes

Answer 3

okay, do you have a specific goal in mind like maximizing the distance or height of the jump?

Answer 4

this is what i have so far, tell me if its ok but I'm open to changing it too:

the pole vaulter runs 100m as fast as she can in 1o seconds. this gives her a velocity of 10m/s. The pole vaulter weighs 70kg. The bar is 5 m high. The pole vaulter jumps at an angle of 74 degrees. How long is she in the air? How far foes she travel in the air?

this is just what i came up with

Answer 5

okay, first, only the x-component of her jump will be 10 m/s, if she needs to clear a 5m pole a more relevant question would be with what force does she need to jump with (in the y-direction)

Answer 6

the x-distance question and the time are still good questions

Answer 7

i tried to figure out vix and viy. but it wasn't helping me figure out what i needed i think

Answer 8

her running is only contributing to the Vx component, the Vy will come only from her jump

Answer 9

for initial Vx i did 10cos74= 2.76 m/s
for intial Vy i did 10sin74= 9.61 m/s

Answer 10

but then thats not for the jump I'm guessing its just for the run to the jump right?

Answer 11

if she is running parallel to the ground, than the angle is 0

Answer 12

so Vx= 10 m/s and Vy= 10 m/s*sin(0) = 0

Answer 13

is the 0 just for the run before she jumps?

Answer 14

asking what her Vy would have to be to clear the 5m pole would be a good question too

Answer 15

right, the running is her x-component, the jump is hey y

Answer 16

yes i wanted to figure out what it would take for her to clear the pole too. how would i do that?

Answer 17

use the kinematic equations , or use conservation of energy which is generally easier, you can calculate how much energy it would take to reach 5m given her mass and work backwards from there

Answer 18

`these are the equations i have.

Vf= Vi + gt
change in y= Vit + .5gt^2
change in x= Vxt
Vfy^2= Viy^2 + 2g(change in y)

Answer 19

i need help solving it. i tried but i couldn't do it

Answer 20

okay, try using energy:

her kinetic energy (from her y-velocity) must be equal to her gravitational potential energy at 5m of altitude.

Kinetic Energy = (1/2)*mv^2
Gravitational Potential energy (close to earth's surface) = mgh

then equate the gravitational potential energy to her kinetic energy, the velocity you are solving for is her Vy component

Answer 21

i have to go to class but ill check back later so let me know if your still having trouble

Answer 22

ok thanks! i will still need help with solving the projectile motion of it. because i have to calculate stuff using a minimum of 2 concepts, so i can do energy, projectile motion and a few other things

Answer 23

well here you are using potential and kinetic energy as well as conservation of energy, so that 3 :P

Answer 24

energy only counts as one concept for my teacher unfortunately :(

Answer 25

im also going to do the acceleration the vaulter has when sinking in to the cushion, but i also need help.