Most people know that kinetic energy is the amount of energy an object has because it’s moving, but what about potential energy? Potential energy is the ability to do work.
The greater the potential for doing work (the higher its value), the more likely a certain force will be able to move it. For example, if you were trying to pull a heavy box across your floor, you would need more effort and power than if you were pulling a light one. You also need more power when there are stairs involved since they make it harder for gravity to pull the box down each stair.
The faster an object moves – or how quickly – depends on two things: its velocity and acceleration. Acceleration is defined as “a change
in velocity over time.” So, the more quickly an object changes its speed in a given direction and timeframe, the higher its acceleration.
In order to find how fast an object is moving – or what it’s velocity is – you need to know three things: (a) where did it start from? That would be zero velocity.
(b) how much time has passed? and (c) what is its current velocity?
It’s easy to find the answer when you only need two of these variables. For example, if a car accelerates from zero miles per hour in one second, that would mean it has an acceleration of 60 mph/sec-squared.
The more variables, the more complicated it gets. Let’s say a car accelerates from zero miles per hour in one second, and then decelerated to zero miles per hour after two seconds. That would mean its acceleration is -60 mph/sec-squared (negative because of our sign convention). In this case, we need
to find the total time it has been accelerating, and then add on what its velocity is at that point.
It’s also worth noting that acceleration doesn’t need to be constant. For example, if a car accelerated from zero miles per hour in one second, but decelerated by 50 mph/sec-squared after two seconds .
That would mean it has an acceleration of -50 mph/sec-squared.
The car’s velocity at one second would be 0 + 50 = 50 miles per hour, and the velocities at two seconds are 0 (because we’re decelerating) plus 40 because our acceleration is negative (-40). The total time accelerating is one second, so the total velocity is 50 + 40 = 90 miles per hour.
There’s a lot more to acceleration than just the final velocity. For example, what if you started accelerating at 0 mph/sec-squared and then it took one second before your velocity was 50 mph? You would have an initial speed of zero miles per hour because that is how fast you were going when you accelerated from rest (in this case, zero). And that would be a velocity of 50 miles per hour!
The acceleration formula is:
a = vf-vi (where “v” means the final speed after an amount of time, and “i” represents the initial speed)
So in this example you would have: 50 – 0 = 50 mph.
A negative answer means that you started with a higher initial speed.
But how fast does my object move when its potential energy is -40? Well, because the acceleration formula can be rearranged to solve for vf and vi: 40 = 50-0, so we know that our final velocity will be 0 mph! And if our initial speed was -40 mph, we would have a final velocity of 40 miles per hour.
In this formula, “a” is the acceleration (either in meters per second or miles per hour), and “vf” is your final speed. So if you have an initial velocity of 40 mph and accelerate at a rate of 20 mph/sec to 0, then after one sec you’ll be going 60 mph.
So in this example, the final velocity is 0 mph. A negative answer means that you started with a higher initial speed. But how fast does my object move when its potential energy is -40? Well, because the acceleration formula can be rearranged to solve for vf and vi: 40 = 50-0, so we know that our final velocity will be 40 mph.
In this formula, “a” is the acceleration (either in meters per second or miles per hour), and “vf” is your final speed. So if you have an initial velocity of -40 mph and accelerate at a rate of 20 mph/sec to 0, then after one sec you
Conclusion paragraph:
In order to understand both kinetic and potential energy, it’s helpful if you think about them like this. Kinetic energy is the amount of work an object can do because it’s moving. Potential energy is the ability to do work even when a body isn’t in motion-it just needs some help (like being lifted up). Together, these two types of energies are sometimes called “work.”
