Question

A crossbow is fired horizontally off a cliff with an initial velocity of 15 m/s. If the arrow takes 4s to hit the ground, what is the range of the projectile?

Answer 1

The range of the projectile is 60 m

Step-by-step explanation:

Horizontal Motion

When an object is thrown horizontally with a speed vo from a height h, it describes a curved path ruled exclusively by gravity until it eventually hits the ground.

The horizontal component of the velocity is always constant because no acceleration acts in that direction, thus:

`v_x=v_o`

The vertical component of the velocity changes in time because gravity makes the object fall at increasing speed given by:

`v_y=g.t`

The horizontal distance is calculated as a constant speed motion:

`x = v_x.t`

Knowing the crossbow is fired horizontally at vo=vx=15 m/s and it takes t=4 s to hit the ground, thus the range of the projectile is:

x = 15*4 = 60

The range of the projectile is 60 m