It occurs when energy is supplied or withdrawn :)
At the ground the ball will always have velocity along the direction of gravity. If upward motion is taken positive it will always have negative velocity at the ground because, if the ball was given an initial upward velocity then gravity will decelerate it and bring it down with a negative final velocity. If the ball is given an initial downward velocity then the ball will be further accelerated by gravity in the downward direction only, again maintaining negative direction. The magnitude however in both cases will be different. the final velocity at the ground will have higher magnitude in case of elevator moving downwards.
Complete Question:
Football player A has a mass of 110 kg, and he is running down the field with a velocity of 2 m/s. Football player B has a mass of 120 kg and is stationary. What is the total momentum after the collision?
Answer:
Total momentum = 220 Kgm/s.
Explanation:
<u>Given the following data;</u>
For footballer A
Mass, M1 = 110kg
Velocity, V1 = 2m/s
For footballer B
Mass, M1 = 120kg
Velocity, V1 = 0m/s since he's stationary.
To find the total momentum;
Momentum can be defined as the multiplication (product) of the mass possessed by an object and its velocity. Momentum is considered to be a vector quantity because it has both magnitude and direction.
Mathematically, momentum is given by the formula;
a. To find the momentum of A;

Momentum A = 220 Kgm/s.
b. To find the momentum of B;

Momentum B = 0 Kgm/s.
c. To find the total momentum of the two persons;
Substituting into the equation, we have;

<em>Total momentum = 220 Kgm/s. </em>
Answer:
After 12 seconds, the area enclosed by the ripple will be increasing rapidly at the rate of 1206.528 ft²/sec
Explanation:
Area of a circle = πr²
where;
r is the circle radius
Differentiate the area with respect to time.

dr/dt = 4 ft/sec
after 12 seconds, the radius becomes = 
To obtain how rapidly is the area enclosed by the ripple increasing after 12 seconds, we calculate dA/dt


dA/dt = 1206.528 ft²/sec
Therefore, after 12 seconds, the area enclosed by the ripple will be increasing rapidly at the rate of 1206.528 ft²/sec
Explanation:
Use Pythagorean theorem:
r² = x² + y²
r² = (-6.46 m)² + (-3.78 m)²
r = 7.48 m