Which best describes acceleration

By the way if you have learned about "centripetal acceleration", that is acceleration with no speed change, just direction. I haven't learned about that yet, but thank you for telling me! Now when that lesson comes up I'll already have an idea about what it is. Often if negative it is called de-acceleration but not by physicists :. First Name. Your Response. What is a newton? A tennis player swings and hits the ball away. How does the force of the tennis racket affect the motion of the ball?

On planet x, an object weighs On planet B where the magnitude of the free fall acceleration is 1. The acceleration of gravity is 9. Need serious help!! How can the momentum of a moving object be found? By multiplying its mass by its acceleration. By dividing its change in distance trabeled by the time it travels. By dividing its velocity bu the. Please check my work : 1 Choose the best answer. A Known as the Land of the Midnight Sun. B Three quarters of the distance from the equator to the North Pole.

C In the summer,. Who are you? If an object is not changing its velocity, then the object is not accelerating. The data at the right are representative of a northward-moving accelerating object.

The velocity is changing over the course of time. Anytime an object's velocity is changing, the object is said to be accelerating; it has an acceleration. Sometimes an accelerating object will change its velocity by the same amount each second. This is referred to as a constant acceleration since the velocity is changing by a constant amount each second. An object with a constant acceleration should not be confused with an object with a constant velocity.

Don't be fooled! If an object is changing its velocity -whether by a constant amount or a varying amount - then it is an accelerating object.

And an object with a constant velocity is not accelerating. The data tables below depict motions of objects with a constant acceleration and a changing acceleration. Note that each object has a changing velocity. A falling object for instance usually accelerates as it falls. Our free-falling object would be constantly accelerating. Given these average velocity values during each consecutive 1-second time interval, we could say that the object would fall 5 meters in the first second, 15 meters in the second second for a total distance of 20 meters , 25 meters in the third second for a total distance of 45 meters , 35 meters in the fourth second for a total distance of 80 meters after four seconds.

These numbers are summarized in the table below. This discussion illustrates that a free-falling object that is accelerating at a constant rate will cover different distances in each consecutive second.

Further analysis of the first and last columns of the data above reveal that there is a square relationship between the total distance traveled and the time of travel for an object starting from rest and moving with a constant acceleration. The total distance traveled is directly proportional to the square of the time. For objects with a constant acceleration, the distance of travel is directly proportional to the square of the time of travel. The average acceleration a of any object over a given interval of time t can be calculated using the equation.

This equation can be used to calculate the acceleration of the object whose motion is depicted by the velocity-time data table above. The calculation is shown below. Typical acceleration units include the following:. These units may seem a little awkward to a beginning physics student. Yet they are very reasonable units when you begin to consider the definition and equation for acceleration.

The reason for the units becomes obvious upon examination of the acceleration equation. Since acceleration is a vector quantity , it has a direction associated with it.

The direction of the acceleration vector depends on two things:. The general principle for determining the acceleation is:. This general principle can be applied to determine whether the sign of the acceleration of an object is positive or negative, right or left, up or down, etc.

Consider the two data tables below. In each case, the acceleration of the object is in the positive direction. In Example A, the object is moving in the positive direction i. When an object is speeding up, the acceleration is in the same direction as the velocity. Thus, this object has a positive acceleration.