The driver who finished the race in the least amount of time, came first:
By comparing the speed of each of the drivers, and not distance covered by them–one can establish
that the driver with maximum speed is the winner.
Speed can be defined as “how fast something moves” or it can be explained more scientifically as “the distance covered in a unit of time”.
In daily life we use the first definition and say the faster object has higher speed. Speed does not show us the direction of the motion it just gives the magnitude of what distance taken in a given time. In other words it is a scalar quantity. Speed is directly proportional to the distance and inversely proportional to the time. Motor vehicles commonly use kilometer per hour (km/h) as a unit of speed however in short distances we can use meter per second (m/s) as a unit of speed.
Velocity :
Velocity can be defined as “speed having direction”. velocity is a vector quantity having both magnitude and
direction. We can define velocity as the “rate of change of displacement” whereas “the speed is rate of change
of distance”. While we calculate speed we look at the total distance, however, in calculating velocity we must consider
the direction and in short we can just look at the change in position not the whole distance traveled. If a man walks 5m to east
and then 5m to west speed of that man calculated by dividing total distance traveled which is 10m to the time elapsed, however,
velocity calculated by dividing the displacement to the elapsed time, which is 0m divided elapsed time gives us zero. In other
words, if the displacement is zero we can not talk about the velocity.
The Speedometer of the car gives instantaneous speed:
Average Speed and Instantaneous Speed:
A moving object does not have the same speed during its travel. At a given instant of time what we read from the speedometer
is the instantaneous speed. For example, a car moving with a constant speed travels to another city, it must stop at the signal,
or it should slow down when required. At the end of the trip, if we want to calculate the average speed of the car we divide
total distance to total time taken for the trip.
Average Velocity and Instantaneous Velocity:
The ratio of Displacement to the total time taken gives the Average velocity of an object. Instantaneous velocity is the velocity
at a given instant of time, however, as in the case of speed, average velocity is calculated with displacement over time
interval. We must give the direction with velocity since velocity is a vector quantity however, speed is a scalar quantity and
we do not consider direction.
A sequence of a photo shoot while a car accelerates:
Acceleration:When the velocity of an object changes it is said to be accelerating.
Acceleration is the rate of change of velocity with time, the word acceleration is often used to describe a state of increasing speed. Any change in the velocity of an object results in an acceleration: increasing speed or decreasing speed, or changing direction. A change in the direction of motion results in an acceleration even if the moving object neither sped up nor slowed down. That's because acceleration depends on the change in velocity and velocity is a vector quantity – one with both magnitude and direction. Thus, a falling apple accelerates, a car stopping at a traffic light accelerates, and an orbiting planet accelerates.
Acceleration occurs anytime an object's speed increases, decreases, or changes direction. There are two kinds of acceleration: average and instantaneous. Average acceleration is determined over a “long” time interval. The word long in this context means finite. The velocity at the beginning of this interval is called the initial velocity (v) and the velocity at the end is called the final velocity. In contrast, instantaneous acceleration is measured over a “short” time interval which is finite. Acceleration is the first derivative of velocity with time and the second derivative of displacement with time.
An Airplane generally has a non uniform motion:
Uniform motion: The change in position of an object with respect to time is called as motion, which is measured with respect to a reference frame. Velocity, acceleration, displacement and time are the basic parameters which describe motion. There are basically two types of motion :
- Uniform motion
- Non–uniform motion
- Uniform motion: A motion which covers equal distance in equal interval of time is called a Uniform motion.
For the body to be in the uniform motion, it must be moving in the straight line path. The body going with constant increase
in velocity in equal interval of time is also the uniform motion. The slope of displacement–time graph for uniform
motion is constant and gives constant velocity. Some examples are:
The motion of a free falling body. The motion of a bicycle going down the slope of a road when the rider is not pedaling and wind resistance is negligible. The motion of a ball rolling down an inclined plane. The motion of the Pendulum Clock.
- Non–uniform motion: Nonuniform motion is accelerated motion where the velocity of a body is changing with time. Velocity vectors point in the direction of motion. The acceleration vector points in the direction that the motion is being influenced. If the acceleration of a body is constant, then its velocity is linear and its position function is quadratic.