Is this on the course?

[run-bandit]

will we ever get this sort of thing in physics or is just a random bad textbook question:

A horse rider wants to jump a 3.0 m wide stream. The horse can approach the stream with a speed of 7 m s-1. At what angle must the horse take off? (Hint: you will need to use trigonometric identities from mathematics, or model the situation using a spreadsheet to solve this problem.)   

[appianway]

You could get it, but it's unlikely. I've seen it in the context of VCE before.

[Edmund]

Yeah, that's projectile motion

[TrueTears]

we got this kind of question as a sac once.

[moekamo]

yea if you use the shortcut formula: where is the horizontal range, is velocity, is the launch angle and is acceleration due to gravity, its pretty easy:

degrees


Note: This formula only works for symmetrical cases, ie land at the same level as take off, if this isnt the case use constant acceleration formula to solve vertical and horizontal components.

[QuantumJG]

will we ever get this sort of thing in physics or is just a random bad textbook question:

A horse rider wants to jump a 3.0 m wide stream. The horse can approach the stream with a speed of 7 m s-1. At what angle must the horse take off? (Hint: you will need to use trigonometric identities from mathematics, or model the situation using a spreadsheet to solve this problem.)   

Yes you could get it. Plus it really tests your understanding of projectile motion. You are given the shortcut formulas so it's actually quite easy to solve (plus the trig identities are simple and deriving the formulas is simple).

R = v<sub>x x tflight = v x tflight x cos(θ)

tflight can be found by using:

s = ut + 0.5at²

let s = 0, a = -g, u = vsin(θ)

0 = 0.5t(2vsin(θ) - gtflight)





Because sin(2θ) = 2sin(θ)cos(θ)

And then to find θ, you can say:



and by simple substitution you find θ to be 18.4^o.</sub>



     

[physics]

its everywhere in my physics book dammit!