Why is force mass times acceleration

The difference between these, divided by the time between them, yields the acceleration. A series of results is accumulated in a table. This should also include a column for the manual entry of values for force in newtons. It is informative to display successive measurements on a simple bar chart. Carbon dioxide cylinder Syphon type. The magnetic puck is a small metal ring magnet, of the kind used as field magnets in television sets. It has a metal or card lid. When it is filled with solid carbon dioxide, the puck floats on the sublimed gas.

A kit is available from scientific suppliers. Four pucks are provided, two magnetic, two non-magnetic and made of brass. They are, however, all of the same size and mass and you can stack them one on top of the other. Polish the glass plate using a duster and methylated spirit or window cleaning fluid. Carefully level it using the wedges supplied. The lengths of elastic used with trolleys are not suitable because a smaller force is needed here.

Instead, use a longer length, with one end attached to the top of the puck with sticky tape. The stretch on this must be kept uniform. Here is a convenient technique. Hold the end against a half-metre rule. Ensure that it is always the same distance from the puck. With practice you can produce a fairly steady force.

The start of the motion does not necessarily coincide with an exposure or with an image. A high frequency of exposure is required. This reduces any error in identifying the time of the start of the motion, relative to later images. Long runways or heavy shorter ones should be handled by two persons.

In operation, ensure that a string is tied across the bottom of the runway, to prevent the trolley falling onto the floor or someone's foot. It might not be possible for every group to have three trolleys, and so groups may need to share. To ensure the elastic cords given to one group of students all stretch by the same amount for the same force, set up a testing rig as shown in the diagram.

Oil the bearings on the trolley wheels. Do not use trolleys with bent axles through dropping. Ensure the runway and the trolley wheels are clean. Finding average acceleration with a ticker-timer. In operation ensure that a string is tied across the bottom of the runway, to prevent the trolley falling onto the floor or someone's foot. It might not be possible for every group to have three trolleys at all times, and so groups may need to share. This activity demonstrates that inertia depends on mass and not on any other interpretation of size.

Force, mass and acceleration are inter-related quantities. Clearly, there are dangers of collisions or of students falling off skateboards. The activity should be done in a reasonably large, clear space, on a level floor or surface. Commercial trolleys are ideal. They have an attachment so that a wheel drives a dynamo attached to a meter, which acts as a speedometer.

This is valuable, but is not essential. So that trolleys can be accelerated with fairly constant force, put a strong spiral spring between the spring balance and the trolley.

This smooths out jerkiness of motion. This experiment illustrates a fundamental point about the nature of measurement, as well as providing a way of measuring the speed of a trolley. Clearly there are dangers of collisions. The meter attachment is a special device, recommended not for general use but for the learning involved in setting it up and calibrating it.

It is difficult to do with precision. Ensure that a string is tied across the bottom of the runway to prevent the trolley falling onto anyone. It is important that the balance is lightweight, so that it does not add to the mass. It is also better if the balance is not too precise.

Teaching Guidance for Play back the video frame by frame and place a transparent acetate sheet over the TV screen to record object positions. You need a camera that will focus on images for objects as near as 1 metre away. The camera will need a B setting, which holds the shutter open, for continuous exposure.

Use a large aperture setting, such as f3. Digital cameras provide an immediate image for analysis. With some cameras it may be necessary to cover the photocell to keep the shutter open. Set up the stroboscope in front of the camera so that slits in the disc allow light from the object to reach the camera lens at regular intervals as the disc rotates. Lens to disc distance could be as little as 1 cm. The slotted disc should be motor-driven, using a synchronous motor, so that the time intervals between exposures are constant.

Do this symmetrically. For example, a disc with 2 slits open running at rpm gives 10 exposures per second. Units for force, mass, and acceleration. When you multiply a kilogram mass unit times a meter per second squared acceleration unit you get a kilogram-meter per second squared. So a unit for force is actually the kilogram-meter per second squared.

However, no one really says that. The unit for force is named after Isaac Newton, and it is called the 'Newton', abbreviated 'N'. One Newton is one kilogram-meter per second squared. Another almost identical way to think about the force unit is that one Newton is the size of a force needed to accelerate a mass of one kilogram at a rate of one meter per second squared, as in:.

Also presented is the algebra used to rearrange the formula when solving for mass or acceleration. After going through the above slideshow, one might wonder how the units for these equations resolve. For example, the following is true:. But how does an acceleration unit on the left become the same as a force unit divided by a mass unit on the right?

All of this is explained in the following scrolling panels. Each problem page has a back button that will return you to this page. First, recall that when we multiply a scalar times a vector, the result is a vector that has the same direction as the original. So if we multiply scalar 2 times vector P we get a vector as the result which has the same direction as vector P.

We could give this result vector a name, say Q. This is all shown in the following animation:. Note that the right side of the equation is mass times acceleration. Mass is a scalar, and acceleration is a vector. So the right side of this equation is a scalar times a vector.

This multiplication yields a vector that is called the force vector, or F , which is on the left side of the equation. As above with P and Q , vector a is in the same direction as vector F. Therefore, the acceleration of an object is in the same direction of the applied net force. Here is another animation showing all of this for the a and F vectors:. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search.

My teacher said that the force is mass times acceleration. But, how are mass and acceleration related to force? Unfortunately, we don't know everything. And the relationship you mention is one of those things - we know this is how the world works; but we don't know why. Newton "discovered" and formulated this law by doing many, many experiments. If you lift your pen and let go, it falls. It also falls when you do it again. And again.

And times. And also when people do it times. In the end you start trusting this as something that will always happen - you can't prove it, but you still trust it to happen again next time you try. Newton saw in this way that this just happens to be how the world works.

It isn't an explanation, just an observation of the nature of the world. We call it a law of nature ; it can't be proven, but we trust it to work because it has done so many times before.

Therefore there is no answer to a question about why this law is the case. We don't know and can't explain it - we just know that this is how it all works. The force will change the momentum of the object. I think you might be asking why mass and acceleration are related. If so, I can help. Force is a measure of mass and acceleration that humans have agreed to use.

The only reason the two properties are related is because physicists have defined force as being mass times acceleration. The use of Newton's Second Law as a definition of force has been disparaged in some of the more rigorous textbooks, because it is essentially a mathematical truism. Wikipedia article on Force. Newtons second law states that change in linear momentum is proportional to the external force acting on the body and us in the ditection of the external force.

Acceleration is a change in velocity. Newton found that an unbalanced force is required to change an object's velocity. Newton's Second Law of Motion defines force in this way: Acceleration is produced when a force acts on an object.

This relationship between mass and acceleration provides a useful way to define and measure forces that act upon objects and change their velocities. Newton was the first one to quantify physical physica means nature in some language I believe observations. He built on Galileo's concepts of inertia. What you must understand that the quantitative aspects of any physical entity are things which are created by us to 'gauge' their qualitative counterparts.