Answer:
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Explanation:
ANSWER:
250 J
STEP-BY-STEP EXPLANATION:
F = 20N is required to stretch the spring by 4 meters
We know that the force is equal to:
We solve for k (spring constant):
The work done in stretching the spring is given by the following equation (in this case the stretch is 10 meters:
The work required is 250 joules.
Distance (s) =20 m
Initial velocity =0 m/s
g=10 m/s²
By using the formula:
v²= u²+ 2as
v²=0²+ 2×10×15
v²= 300
V= 10root over 3
For calculating time,
v= u+ at
10 root over 3 = 0+ 10t
10 root over= 10t
t = 1 root over 3
t = 1.73 s
The the stone will hit the ground with a velocity of 10 root over 3 m/s in 1 root over 3 sec.
A person riding in an elevator subjected to a series of unbalanced forces depending on the direction the elevator is travelling.
Two forces are acting on the person; the force of gravity and the upward normal force from the elevator.
When the elevator is going upwards with acceleration a, the person feels heavier than his normal weight, due to the upward normal force being greater than the person's weight. N = mg + ma
When the elevator is moving downwards with acceleration a, the person feels lighter due to the downward normal force being less than the person's weight. N = mg - ma
However, when the elevator is moving up or down at constant velocity ie. acceleration a = 0, the person experience a normal force equal to weight. N = mg
When the elevator is moving downwards with acceleration a = g, the person experiences weightlessness. N = (mg - mg) = 0
<span>A change from one form of energy
into another is called conservation of energy. The answer is letter C. you
cannot create something and destroy it. An example is eating food. You can see
food as how as a physical being. However, when you eat the food, the digestive
enzymes in your stomach helps break down the food into smaller form. The chemical
energy in the food is being changed into mechanical energy. You need food to
perform the necessary activities in your life. </span>
