FearOfPhysics.com: Home

Fearofphysics: Physics problem of the week

# Physics Problem of the Week for Sep 15 2014

 Basketball free throwYou want to make a free throw in basketball. You are standing 4.6 m from the basket, which is 3 m high. You throw the ball at an angle of $30^\circ$, from a height of 1.5 m. With what speed do you need to throw the ball in order to make it into the basket with "nothing but net?"← Previous

1. Create an electronic version of your answer, and post it to the web using Google Docs, Dropbox, Imgur, etc.
3. Paste the share link here:
5. Correct answers will be posted here when the problem expires (typically every Wednesday, when a new problem will be posted).

## Prove you are human

Group solutions work when someone suggests the next step toward this problem's solution.

### Steps accepted thus far

• At 30 degrees, I would start by finding the x and y components of the ball's velocity.

• Here, $v_x=v\cos30$ and $v_y=v\sin30$. So the ball's initial speed to the right is $v_x$ and the initial speed up is $v_y$.

• Let's now see how long the ball is in the air: it starts 1.5 m high and needs to end up 3 m high, given that is is launched vertically at vsin30.

• The time in the air is then $3=1.5+v\sin30t-\frac{1}{2}gt^2$. We need to solve this for $t$.

• We also know that in the same time $t$, the ball should go horizontally 4.6 m, or $4.6=0+vcos30t$.

• These are 2 equations and two unknowns in $v$ and $t$. I used Wolfram Alpha to solve them and got $v=7.7$ m/s.

Logon to suggest the next step in solving this problem.

Contact: fopc...@gmail.com