For example, when a car travels at a constant speed, the driving force from the engine is balanced by resistive forces such as air resistance and friction in the car’s moving parts. The resultant force on the car is zero.

The acceleration of a car that travels in a straight line at a constant speed of 100 km/h is zero. Average acceleration = (change in velocity)/(time it takes). Since the car’s change in velocity is zero, its acceleration is zero.

While the speed of the object is constant, its velocity is changing. Velocity, being a vector, has a constant magnitude but a changing direction.

Definition: When the speed of an object remains the same – it does not increase or decrease – we say it is moving at a constant speed.

1. constant speed.
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At constant speed, acceleration is zero, no doubt. Velocity is a vector quantity that has its magnitude+ direction. The magnitude of instant velocity termed as speed. Speed is a scalar quantity.

At this point, the students technically already have enough evidence to see that a constant force will mean the object will move with a continuously increasing speed (if the force is in the same direction as the motion of the object).

Constant applied force means constant velocity, thus 0 acceleration, thus 0 net force according to the [math]F=m a[/math] formula.

Constant speed is shown by straight lines on a graph. steeper dashed line got there before the other one: A steeper line indicates a larger distance moved in a given time. In other words, higher speed. Both lines are straight, so both speeds are constant.

In a distance-time graph, the slope or gradient of the line is equal to the speed of the object. The steeper the line (and the greater the gradient) the faster the object is moving.

If an object exhibits non-uniform motion, a position-time graph of the motion will be curved, not straight. If you graph the velocity of the object vs. time, then this graph will tell you how quickly the velocity is changing, a quantity called acceleration.

According to Newton’s second law of motion, the acceleration of an object equals the net force acting on it divided by its mass, or a=Fm. This equation for acceleration can be used to calculate the acceleration of an object when its mass and the net force acting on it are known.

If the acceleration is constant, it is possible to find acceleration without time if we have the initial and final velocity of the object as well as the amount of displacement. The formula v2=u2+2as where v is the final velocity, u is the initial velocity, a is the acceleration and s is the displacement is used.

Calculating acceleration involves dividing velocity by time — or in terms of SI units, dividing the meter per second [m/s] by the second [s]. Dividing distance by time twice is the same as dividing distance by the square of time. Thus the SI unit of acceleration is the meter per second squared .

The most common definition of weight found in introductory physics textbooks defines weight as the force exerted on a body by gravity. This is often expressed in the formula W = mg, where W is the weight, m the mass of the object, and g gravitational acceleration.