- Speed=distance / time
- Velocity=displacement / time
- Accleration=velocity / time
- Force=mass X accleration
- Work=Force X Distance
- Power=Work / Time
Speed Equation (s=d/t)
Physics has many different equations. In order to learn the more advanced equations, you need a good knowledge of the basic ones and speed is a good place to start. To find the average speed of an object, you must divide the distance the object has traveled by the time it took the object to travel that distance. For instance, if you throw an object and it travels 10 feet in 2 seconds, you would divde 10 by 2, equaling 5 feet per second (about 3.4 miles per hour).
Note: if you need to convert feet per second to miles per hour, you multiply by 3600 and divide by 5280. For miles per hour to feet per second, you multiply by 5280 and divide by 3600.
Velocity Equation (v=x/t)
Velocity and speed are similar but have a key difference in that velocity involves direction. We say that Velocity is displacement, or the distance an object is from it’s starting point, divided by the time it takes the object to travel that distance. So if you were to run 1 mile around a track in .1 hours (6 minutes) and you ended at the same spot you started in, your average speed would be 10 miles per hour (1 mile traveled divided by .1 hours) but your velocity would be 0. Why? your displacement was 0 and 0 divided by anything is 0. Because you didn’t travel anywhere from your original location, you’re displacement was 0. Another example is you jog 1 mile north and then 2 mile east in .5 hours (30 minutes) you’re speed would be 6 miles per hour (3 miles total distance divided by .5 hours). The velocity, however, would be different because it involves displacement (the distance from your starting point) rather than the total distance you traveled.
Accleration Equation (a=v/t)
This physics equation is slightly more advanced than speed and velocity. It can be summarized as your change in velocity over a certain period of time. For instance you could be jogging at 3 m/s (meters per second) and then speed up to a sprint at 5 m/s in 2 seconds. Then your accleration would equal 1 m/s/s. This is because the change in velocity, which can be calculated by subtracting your final velocity by your initial velocity (in this case, you would solve 5 m/s – 3 m/s) is 2 m/s and the time it takes to change that velocity is 2 seconds so your accleration is 1 m/s/s.
Now lets say you take a break from sprinting and walk at 1 m/s. It took you another 2 seconds to decrease your velocity to that value. Then you would be going through the process of negitive acceleration (or deaccleration, which you might hear in everyday conversation). This is because you are accelerating at a negitive rate, 1-5/2=-4/2=-2m/s/s
Note: the units for acceration can be written as m/s/s or m/s^2 Force Equation (f=ma)
Now we get into concepts beyond speed and velocity. When you drop a ball off a 2-story building, gravity pulls the object down at 10 m/s/s. On Earth, thats approximatly the accleration of a falling object. If the ball weighs 2 kg, then the force of the object is 20 N (Newtons). If you multiply the mass by the accleration you get the force an object exerts on another object (in this case, the ball on the ground).
Work Equation (w=fd)
When you apply force to an object and move it a certain distance, you are doing work. In everyday life, most of us refer to work as filling out papers, mowing the lawn, doing the dishes, etc. In physics, work is the force applied to an object times the distance the object travels. If you push an object with a force of 10N and the object moves 3 meters, the work done is 30 J (joules).
Power Equation (P=w/t)
When you lift a barbell, you are doing work by lifting the barbell. Lets say that you and a friend both lift a 60 kg barbell 2 meters. Then you would both be doing the same amount of work. However, your friend takes 2 seconds to lift it while you only take 1. If you divide the work done on the barbell (120 J) by the time it took both of you to lift the barbell, you would have used 120 W (watts) of power while your friend has only used 60 W.
These are only some of the basic equations of physics. If you want to learn more about physics I suggest you take a course or get a book because there is much more to learn on the subject. It’s good to have a solid understanding on the world we live in!