Answer: 3.21 N


For weight, we will multiply by 

Hence, the rock would weigh 3.21 N.
The answer would probably be D
Answer:
The height of the bridge is 14.5
Explanation:
Given the following data
t = 2.9 seconds
g = +10m/s^2
Using the below formula
H = ut + 1/2gt^2
Since the initial velocity u = 0
Then, H = 1/2gt^2
H = 1/2 x 2.9 x 10
H = 2.9 x 10 / 2
H = 2.9 x 5
H = 14.5