All vehicles are required to stop within 15 FEET of the railroad crossing when a train is approaching.
Answer:
<em>The second ball has four times as much kinetic energy as the first ball.</em>
Explanation:
<u>Kinetic Energy
</u>
Is the type of energy an object has due to its state of motion. It's proportional to the square of the speed.
The equation for the kinetic energy is:

Where:
m = mass of the object
v = speed at which the object moves
The kinetic energy is expressed in Joules (J)
Two tennis balls have the same mass m and are served at speeds v1=30 m/s and v2=60 m/s.
The kinetic energy of the first ball is:



The kinetic energy of the second ball is:



Being m the same for both balls, the second ball has more kinetic energy than the first ball.
To find out how much, we find the ratio:

Simplifying:

The second ball has four times as much kinetic energy as the first ball.
The only correct statement on the list is choice-A./
Answer:
Armando's weight ,restored force created by the trampoline
a harmonic movement within the trampoline
Explanation:
In a trampoline we have two forces that actuate Armando's weight and the restored force created by the trampoline that depends on the deformation distance of the elastic canvas.
Amando's weight is vertical and directed towards the center of the Earth and has a constant value, this weight is balanced with the elastic force the springboard exerts on Armando in a vertical direction.
In general, when entering the trampoline, a small jump is made, this creates a speed that deforms the canvas until the speed is reduced to zero, at this point the elastic force is greater than the weight and the boy begins to climb, After the boy leaves the canvas he meets only the force of gravity and his speed decreases to zero and begins his fall.
In Summary Armando is in a harmonic movement within the trampoline