Forrest drops a rock from a bridge to the water below. The rock entered the water at a speed of 19.6 m/s. How long did it take the pebble to reach the water from the bridge? [s=d/t]

It took the rock 2 seconds to get to the water from the bridge.

Explanation:

Since Forrest drops the rock, it means its initial velocity is zero, and because it is freely falling under the influence of gravity, after time it will gain a velocity of

,

solving for we get:

Since in our case the velocity the rock gained was and the acceleration due to gravity is , we have

Thus, the time took the rock to reach the water from the bridge was 2 seconds.

1.195000

explanation:

total mass=0.0117+0.0137+0.0881+0.0111

total mass= 0.01172kg

total velocity = 0.283-0.743+0.871-0.799+0.155+0.637+0.301=0.102

momentum=mv=0.1172*0.102=1.195000//