#1

So I'm having some issues solving this physics problem dealing with motion in multiple dimensions.

A 2.00-m-tall basketball player wants to make a goal from 10.0 m from the basket. If he shoots the ball at a 45 degree angle, at what initial speed must he throw the basketball so that it goes thought he hoop without striking the backboard. The hoop is 3.05 m high.

I haven't done much complicated physics yet. All I've done so far are the basic equations of motion: v = v0 + a t, x = v0 t + 1/2 a t^2, v^2 = v0^2 + 2 a x, that kind of stuff. In terms of trigonometry, I don't use anything but the basic sin, cos, tan stuff.

A 2.00-m-tall basketball player wants to make a goal from 10.0 m from the basket. If he shoots the ball at a 45 degree angle, at what initial speed must he throw the basketball so that it goes thought he hoop without striking the backboard. The hoop is 3.05 m high.

I haven't done much complicated physics yet. All I've done so far are the basic equations of motion: v = v0 + a t, x = v0 t + 1/2 a t^2, v^2 = v0^2 + 2 a x, that kind of stuff. In terms of trigonometry, I don't use anything but the basic sin, cos, tan stuff.

*Last edited by LiquidTension99 at Sep 29, 2008,*

#2

and thats all you need, seeing as the ball should travel in a perfect arc (in theory). and you already know the slope at one point, and the predicted slope at the other, so it shouldn't be that hard.

#3

and thats all you need, seeing as the ball should travel in a perfect arc (in theory). and you already know the slope at one point, and the predicted slope at the other, so it shouldn't be that hard.

Well I believe you when you say that I have all that I need, but I've never talked about the slope of the shot or whatever. Just stuff relating to speed, acceleration, time, and distance. Maybe that's what you mean, but I need some clarification. I know it's not super-advanced, I sort of just don't know where to start on this one.

#4

ill get my old yr 12 physics book and get back to you

#5

a= acceleration

u= initial velocity

s= displacement

t= time

displacement in x direction = 10

displacement in y direction = 3.05-2 = 1.05

initial velocity in x direction = u cos45

initial velocity in y direction = u sin45 = u cos(90-45) = u cos 45

using s = ut + 0.5at^2,

in x direction: 10 = (u cos45)(t) + 0.5(0)(t^2) ...Eqn 1

in y direction: 1.05 = (u cos45)(t) + 0.5(-9.81)(t^2) ...Eqn 2

Eqn 1 - Eqn 2,

10-1.05 = -(-4.905)(t^2)

t = 1.351

sub t = 1.351 into Eqn 1,

u cos45 = 7.402

u = 10.468

I think its right.. would someone double check?

u= initial velocity

s= displacement

t= time

displacement in x direction = 10

displacement in y direction = 3.05-2 = 1.05

initial velocity in x direction = u cos45

initial velocity in y direction = u sin45 = u cos(90-45) = u cos 45

using s = ut + 0.5at^2,

in x direction: 10 = (u cos45)(t) + 0.5(0)(t^2) ...Eqn 1

in y direction: 1.05 = (u cos45)(t) + 0.5(-9.81)(t^2) ...Eqn 2

Eqn 1 - Eqn 2,

10-1.05 = -(-4.905)(t^2)

t = 1.351

sub t = 1.351 into Eqn 1,

u cos45 = 7.402

u = 10.468

I think its right.. would someone double check?

#6

i believe that is correct ^^^

edit: nice work btw dude

edit: nice work btw dude

*Last edited by boj at Sep 30, 2008,*

#7

beat me to ita= acceleration

u= initial velocity

s= displacement

t= time

displacement in x direction = 10

displacement in y direction = 3.05-2 = 1.05

initial velocity in x direction = u cos45

initial velocity in y direction = u sin45 = u cos(90-45) = u cos 45

using s = ut + 0.5at^2,

in x direction: 10 = (u cos45)(t) + 0.5(0)(t^2) ...Eqn 1

in y direction: 1.05 = (u cos45)(t) + 0.5(-9.81)(t^2) ...Eqn 2

Eqn 1 - Eqn 2,

10-1.05 = -(-4.905)(t^2)

t = 1.351

sub t = 1.351 into Eqn 1,

u cos45 = 7.402

u = 10.468

I think its right.. would someone double check?

#8

i believe that is correct ^^^

edit: nice work btw dude

Haha thanks man