Answer:
B) Kinetic energy increases, potential energy decreases
Explanation:
In a given system, when a body is at rest, v =0m/s, the kinetic energy is at zero while the potential energy is at maximum. However, when a body is in motion with a velocity = v, the potential energy is at zero while the kinetic energy is at maximum.
Before this happen, the a body at rest (P.E = max) is set on motion, the kinetic energy gradually increases till it converts all the potential energy in the system to kinetic energy and then reverses back when the body goes to rest again.
In this case, before the batter hits the ball, the kinetic energy was at zero while the potential energy was at maximum. However, when he hits the ball and sets it into motion with a velocity V, the potential energy converts to kinetic energy and moves the ball with that energy till it has expanded it and comes to rest.
Potential Energy → Kinetic Energy → Potential Energy.
That's how the system keeps changing.
It totally depends on what kind of wave you're talking about.
-- a sound wave from a trumpet or clarinet playing a concert-A pitch is about 78 centimeters long ... about 2 and 1/2 feet. This is bigger than atoms.
-- a radio wave from an AM station broadcasting on 550 KHz, at the bottom of your radio dial, is about 166 feet long ... maybe comparable to the height of a 10-to-15-story building. This is bigger than atoms.
-- a radio wave heating the leftover meatloaf inside your "microwave" oven is about 4.8 inches long ... maybe comparable to the length of your middle finger. this is bigger than atoms.
-- a deep rich cherry red light wave ... the longest one your eye can see ... is around 750 nanometers long. About 34,000 of them all lined up will cover an inch. These are pretty small, but still bigger than atoms.
-- the shortest wave that would be called an "X-ray" is 0.01 nanometer long. You'd have to line up 2.5 billion of <u>those</u> babies to cover an inch. Hold on to these for a second ... there's one more kind of wave to mention.
-- This brings us to "gamma rays" ... our name for the shortest of all electromagnetic waves. To be a gamma ray, it has to be shorter than 0.01 nanometer.
Talking very very very very roughly, atoms range in size from about 0.025 nanometers to about 0.26 nanometers.
The short end of the X-rays, and on down through the gamma rays, are in this neighborhood.
Answer:
Explanation:
When at rest, initial velocity = 0
In 2 seconds, final velocity = 2 m/s
Acceleration = (final velocity - initial velocity) / time
= (2 - 0) / 2
= 1 m/s^2
Answer:
<em>The person delivered a power of 2,558 Watt</em>
Explanation:
<u>Work and Power</u>
Mechanical work is the amount of energy transferred by a force. It's a scalar quantity, with SI units of joules.
Being the force vector and the displacement vector, the work is calculated as:
If both the force and displacement are parallel, then we can use the equivalent scalar formula:
W=F.s
Power is the amount of energy transferred per unit of time. In the SI, the unit of power is the watt, equivalent to one joule per second.
The power can be calculated as:
Where W is the work and t is the time.
If the person lifts a mass of m=200 Kg, then exerts a force equal to its weight:
F = m.g = 200*9.8 = 1,960
F = 1,960 N
The work done when lifting the weight 7 times by a distance of s=2.2 m is:
W = 7*1,960*2.2=30,184
W = 30,184 J
Finally, the power delivered in t=11.8 seconds is:
P = 2,558 Watt
The person delivered a power of 2,558 Watt
Answer:
Balanced forces.
Explanation:
Forces that are opposite in direction, and, equal in size do not cause a change in motion or position are known as balanced forces. When it is applied to an object at rest, the object will not show any movement.
A good example of a balanced force is when we are trying to push a wall, the wall will push back with an opposite but equal force, so, this time neither the wall nor you will move.
