The royal gorge bridge in colorado rises 321 m above the arkansas river. suppose you kick a rock horizontally off the bridge. the magnitude of the rock's horizontal displacement is 45.0 m. find the speed at which the rock was kicked

2.48 m/s

Explanation:

We can use the kinematic equation,

s = ut +½at²

Where

s = displacement

u = initial velocity

t = time taken

a = acceleration

Using the equation in vertical direction,

321 = 0×t +½×g×t², u = 0 because initial vertical velocity is 0

We get t = 8.01 s

Using the equation in the horizontal direction,

52 = u×8.01 +½×0×(8.01)²,. a = 0 because no unbalanced force act on object in that direction

So u = 2.48 m/s

glen is correct.

step-by-step explanation:

glen is correct because when you multiply 4 * 2 = 8.

and 4 * 3 = 12.

atomic = no of protons.

mass number-atomic number = neutron number