Wow! Very simple. Use the equation for momentum which is p=mv. You know your momentum and velocity, so do 120=m(4), now solve for m, which is 30. The mass of the child is 30 kg
They can pretty much be by water i think
<span>No, because the truck applies more pressure than the bridge can support.</span>
A force is a push or a pull that acts upon an object as a results of its interaction with another object. ... These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is: For every action, there is an equal and opposite reaction.
Answer:

Explanation:
Given data
Mass m=1.2 g=0.0012 kg
diameter d=0.76 m
Friction Force F=3.6 N
To find
Velocity v
Solution
From the Centripetal force we know that

Where m is mass
v is velocity
r is radius
Substitute the given values to find velocity v
So
