Projectile Motion Q (1 Viewer)

[kononi]

On the planet Elvis, an astronaut kicked a stone at an angle of 45 degrees to the horizontal. The stone's initial speed was 12ms-1. The stone traveled 25m horizontally before hitting the ground. What is the value of 'g' on Elvis?

The answer is 5.76ms-1 but I can't get to it. Any ideas?

 

[anon09]

u = 12ms-1

ux = 12cos 45 and uy = 12cos 45 = 6sqroot2


Using sx = uxt

25 = 6sqroot2t

t = 25/6sqroot2


Using sy = uyt + 1/2ayt^2

0 = 6sqroot2 x (25/6sqroot2) + 1/2 x (25/6sqroot2)^2 x a

0 = 25 + (625/144)a

(625/144)a = -25

a = -5.76ms-1 (assuming up is positive)

Therefore, the value of gravity on Elvis is 5.76ms-1

 

[kononi]

Thanks for that! =]

 

[anon09]

That's cool!

I think it's hilarious that Elvis is now considered a planet.