 
This is my van. It demonstrates speed, acceleration, and velocity. Speed is the rate or a measure of the rate of motion, and is usually measured in distance traveled divided by the time of travel. According to my speedometer, I was traveling at 38 mph when I snapped this picture. The speed changes, depending on how much pressure is applied to the gas pedal. Since I may be traveling faster in some places than in others, I can figure my average speed. Average speed is figured by taking the total miles I traveled between my starting point and my destination and then dividing that by the time it took me to get there. If, for instance, I was traveling from Yankton, SD to Columbus, NE, and it took me an hour and a half to get, there, I could divide 100 miles by 90 minutes and my average speed would be 66 mph.
I could also use this information to calculate my velocity. Velocity is simply a vector quantity whose magnitude is a body's speed and whose direction is the body's direction of motion. So, in regards to my trip to Columbus, my velocity would be approximately 66 mph to the south.
While my van is not as small as a compact car, its mass is still pretty light compared to other vehicles in the same size range. Mass is a property of matter equal to the measure of an object's resistance to changes in either the speed or direction of its motion. The mass of an object is not dependent on gravity and therefore is different from but proportional to its weight. Being a lighter weight vehicle, my van requires a lesser amount of force to accelerate than most vehicles in its size range.
When Kaleb is not using his lawnmower, it is in a state of inertia. Inertia is the tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight-line motion to stay in motion in a straight line unless acted on by an outside force. Since no one is touching the lawnmower, it is not moving in any way, and so it is in a state of inertia.
When in this state of rest, the lawnmower also shows the equilibrium rule. The equilibrium rule is the vector sum of forces acting on a non-accelerating object equals zero. Since the lawnmower is not moving, the sum of the forces acting on it equal zero.
However, when Kaleb decides to use his lawnmower, he is able to demonstrate friction and the equilibrium rule. Friction is any force that resists the relative motion or tendency to such motion of two bodies in contact. In this case, the friction is between the wheels of the lawnmower and the carpet. Each is trying to push the lawnmower in a different direction. This picture also demonstrates support force. Support force is any force that supports an object against gravity. Kaleb is leaned so far into the lawnmower that if it were not there, he would fall down. Instead, the lawnmower holds him up against gravity and works with him instead of against him. In the same way, Kaleb is keeping the top of the lawnmower from giving in to the gravitational pull and hitting the floor. Since both Kaleb and the lawnmower are working in an equal fashion, equilibrium of moving things exists. It always takes more than one force for anything to be in equilibrium. The net force, or the sum of all the forces acting on the lawnmower, is always working with the net force acting on Kaleb.
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