Posted by **Ligu** on Friday, September 24, 2010 at 3:43am.

Consider a projectile fired horizontally from a cliff of a given height. With what speed must it be fired so that it makes a 45 degree angle with the ground when it hits

- physics -
**MathMate**, Friday, September 24, 2010 at 9:52am
It hits ground with 45° angle when the vertical velocity, vy, is the same as the horizontal velocity, vx, which equals u (initial velocity) if the projectile is fired horizontally and ignoring air-resistance.

vx=u

Let H=given height of cliff

vy²-0²=2gH

vy²=2gH

since vy=u,

u²=2gH

u=√(2gH)

## Answer this Question

## Related Questions

- Physics - a) A cannonball is fired horizontally from the top of a cliff. The ...
- physics - A projectile is fired at an angle of 30ᵒ above the horizontal ...
- Physics - Someone posted the question below, stating that they knew the answer ...
- Physics - A projectile is fired with an initial speed of 31.0 at an angle of 10....
- Physics - A projectile is fired with an initial speed of 28.0 m/s at an angle of...
- PHYSICS! - A projectile is fired with an initial speed of 32.5 m/s at an angle ...
- PHYSICS! - A projectile is fired with an initial speed of 32.5 m/s at an angle ...
- physics - 48 kg projectile is fired at an angle of 30 degree above the ...
- physics - 'a 48 kg projectile is fired at an angle of 30 degree above the ...
- physics - a projectile with a muzzle velocity of 550 m/s is fired from the a gun...

More Related Questions