Content

• Reduced Formula
• Steps
• Advice

Speed ​​is how fast it is moving in a certain direction of an object. Mathematically, speed is often thought of as the change in the position of an object over time. This basic concept is present in many physics problems. Which formula to use depends on what is known about the object, in order to choose the right formula, read this article carefully.

Reduced Formula

• Average speed =
  • the last position the original position
  • the end of the initial moment
• The average velocity at acceleration is constant =
  • initial speed final velocity
• Average speed if acceleration is constant equal to 0 =
• Final velocity =
  • a = acceleration t = time

Steps

Method 1 of 3: Find Average Velocity

1. 

   
   
   Find the average speed when acceleration is constant. If an object has a constant acceleration, the formula for calculating average velocity is very simple:. In it, is the initial speed, and is the final speed. Just Use this formula if acceleration is constant.
   • For example, consider a train with a constant acceleration from 30 m / s to 80 m / s. So the average speed of the train is.

2. 

   
   
   Formulate formulas using location and time. You can calculate the velocity by the object's change in position over time. This approach can be used in all cases. Note that, unless the object is moving at a constant speed, the result you will be able to calculate will be the average velocity during the movement rather than the instantaneous velocity at some point in time.
   • The formula in this case is, ie "last position - initial position divided by last time - initial time". You can also rewrite this formula as = / _Δt, or "change of location over time".

3. 

   
   
   Find the distance between the starting point and the end point. When measuring velocity, there are only two points to keep in mind, the starting and ending point of the motion. Along with the direction of motion, the start and end points will help us determine Movement in other words change of position of the object in question. It does not take into account the distance between these two points.
   • Example 1: An eastbound car starts at position x = 5 meters. After 8 seconds, the vehicle is at position x = 41 meters. How far has the car moved?
     • The car has moved (41m-5m) = 36 meters to the east.
   • Example 2: A diver leaps 1 meter above a board, then falls 5 meters before hitting the water. How much did the athlete move?
     • In total, the diver had moved 4 meters below the original position, which meant he had moved less than 4 meters, or -4 meters in other words. (0 + 1 - 5 = -4). Although the total travel distance is 6 meters (1 meter up when jumping and 5 meters up when falling), the problem is that the end of the movement is 4 meters below the original position.

4. 

   Calculate change in time. How long does it take the subject in question to reach the end point? There are many exercises that will give this information available. If not, you can determine by subtracting the first point from the end point.
   • Example 1 (cont): The assignment says that the car takes 8 seconds to go from start to finish, so this is the change in time.
   • Example 2 (cont): If the kicker jumps at time t = 7 seconds and resumes the water at t = 8 seconds, the change in time = 8 seconds - 7 seconds = 1 second.

5. 

   Divide the distance by the travel time. To determine the speed of a moving object, we divide the distance traveled by the total time spent and determine the direction of motion, you will get the average speed of that object.
   • Example 1 (cont): The car has traveled 36 meters in 8 seconds. We have 4.5 m / s eastward.
   • Example 2 (cont): The athlete moved a distance of -4 meters in 1 second. We have -4 m / s. (In one-way motion, negative numbers usually imply "down" or "to the left." In this example, we could say "4 m / s in a downward direction").

6. 

   In the case of two-way motion. Not all exercises involve movement in a fixed line. If the object changes direction at some point, you need to graph and solve a geometry problem to find the distance.
   • Listing 3: One person walks 3 meters east, then turns 90 degrees and goes another 4 meters north. How much has this person moved?
     • Draw a graph and connect the start and end points to a line. We get a right triangle, using the properties of the right triangle we will find its side length. In this example, the displacement is 5 meters northeast.
     • Sometimes your teacher may ask you to find the exact direction of movement (upper horizontal corner). You can use the geometric properties or draw vectors to solve that problem.
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Method 2 of 3: Find Velocity knowing Acceleration

1. 

   The formula for the velocity of an object with acceleration. Acceleration is the change of speed. Speed ​​varies evenly when acceleration is constant. We can describe this change by multiplying the acceleration times the following time plus the initial velocity:
   • , or "final velocity = initial velocity + (acceleration * time)"
   • Initial velocity is sometimes written as ("velocity at time t = 0").

2. 

   Calculate the product of acceleration and time. The product of acceleration and time shows how the speed has increased (or decreased) during that time.
   • For example: A train travels north at a speed of 2 m / s and acceleration of 10 m / s. How much does the train speed increase over the next 5 seconds?
     • a = 10 m / s
     • t = 5 seconds
     • Velocity has increased (a * t) = (10 m / s * 5 s) = 50 m / s.

3. 

   Plus initial velocity. When we know the change in speed, we take this value plus the initial speed of the object to get the velocity to be found.
   • Example (continued): In this example, what is the speed of the train after 5 seconds?

4. 

   Determine the direction of movement. Unlike speed, velocity is always associated with the direction of motion. So remember to always note the direction of movement when it comes to speed.
   • In the example above, since the ship is always moving north and has not changed direction during that time, its velocity is 52 m / s north.

5. 

   Solve related exercises. Once you know the acceleration and velocity of an object at any given time, you can use this formula to calculate the velocity at any given time. advertisement

Method 3 of 3: Circular Velocity

1. 

   Formula for calculating the velocity of circular motion. The velocity of circular motion is the speed at which an object needs to achieve to maintain a circular orbit around another object such as a planet or an object of weight.
   • The circular velocity of an object is calculated by dividing the circumference of the orbit by the motion time.
   • The formula is as follows:
     • v = / _T
   • Note: 2πr is the circumference of the trajectory of the motion
   • r is "radius"
   • T is "motion time"

2. 

   Multiply the radius of the trajectory of motion by 2π. The first step is to calculate the perimeter of the orbit by taking the product of the radius and 2π. If you don't use a calculator, you can get π = 3.14.
   • For example, calculate the circular velocity of an object whose radius of trajectory is 8 meters over a period of 45 seconds.
     • r = 8 m
     • T = 45 seconds
     • Circumference = 2πr = ~ (2) (3.14) (8 m) = 50.24 m

3. 

   Divide the circumference by the motion time. To calculate the circular motion speed of the object in the problem, we take the circumference we just divided by the motion time of the object.
   • For example: v = / _T = / _{45 s} = 1.12 m / s
     • The circular motion velocity of the object is 1.12 m / s.
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Advice

• Meters per second (m / s) are standard units of velocity. Check that the distance is in meters and time is in seconds, for acceleration the standard unit is meters per second per second (m / s).