Question

During a hard sneeze, your eyes might shut for $0.5\sec $. If you are driving a car at $90Km/h$ during such a sneeze, how far does the car move during that time?

Answer 1

Hint: Here the speed of the car is given in terms of kilometres per hour convert the speed of the hour in terms of metres per second. One kilometre is equal thousand meters and one hour is equal to three thousand six hundred seconds. Using the speed given called the distance travelled by a car when a person shut their eyes for $0.5\sec $.

Formula used:
${{speed = }}\dfrac{{{{distance}}}}{{{{time}}}}$

Complete step by step answer:
Kinematics is the study of motion of the bodies without considering the cause of motion. Length of actual path between initial and final position is called length. Displacement’s magnitude may or may not be equal to the path length travelled by an object.
Ratio of distance travelled by unit time is called speed. It is a scalar quantity. A body is said to be in uniform motion along a straight line when that body is moving with uniform velocity. A particle moving along a straight-line travels an equal distance in equal intervals of time, then the particle is moving at uniform speed. A particle moving along a straight-line travels unequal distance in equal intervals of time or equal distance in unequal time then the particle is moving with no uniform field.
Conversion of kilometre per hour to meter per second
$90\dfrac{{km}}{h}$ = $90 \times \dfrac{{1000}}{{3600}}\dfrac{m}{s}$
Since one kilometre is equal thousand meter and one hour is equal to three thousand six hundred seconds
The speed of the car moving is $25m/s$.
Now distance is the product of speed of the car and time taken
${{distance = speed \times time}}$
${{distance = 25 \times 0}}{{.5 = 12}}{{.5m}}$

Hence the distance travelled by a car for a time period of $0.5\sec$ is $12.5m$.

Note: Distance and displacement are two different quantities. Distance has magnitude but no direction, whereas the displacement has both magnitude and direction. Displacement’s magnitude may or may not be equal to the path length travelled by an object. Ratio of distance travelled by unit time is called speed.