some one please help fast ..... you have to take one part of square floor ..take out its time taken to cover one lap of that square.....take out its distance covered in 2 min 20sec and it's displacement.....please help i will follow you
Answers
Answer:
Explanation:ime, Speed and Distance
In this lesson we learn to solve problems on speed, distance, time, relative speed and boats and streams etc
Key Concepts
1. Distance = Speed × Time
2. 1 km/hr =
5
18
m/s
3. If the ratios of speed is a : b : c, then the ratios of time taken is :
1
a
:
1
b
:
1
c
Relation between variables:
To distance, Speed and Time both are directly proportional and To speed, Time is inversely proportional.
S
∝
D
and
T
∝
D
i.e. if speed is doubled, distance covered in a given time also gets doubled and ,
S
∝
1
T
i.e. if speed is doubled, time taken to cover a distance will be half.
Average speed is defined as =.
Total distance travelled
Total time taken
Relative speed
If two bodies are moving (in the same direction or in the opposite direction), then the speed of one body with respect to the other is called its relative speed.
Relative speed is a phenomenon that we observe everyday. Suppose you are travelling in college bus and there is a second bus coming in the opposite direction, then it seems that the second Bus is moving much faster than actual. If both the Buses were moving in the same direction at same speeds, they seem to be stationary if seen from one of these Busses, even though they might actually be at a speed of 100 km/hr each. So what you actually observe is your speed relative to the other.
Concepts
1. If two objects are moving in opposite directions towards each other at speeds u and v, then relative speed = Speed of first + Speed of second = u + v.
This is also the speed at which they are moving towards each other or the speed at which they may be moving away from each other.
2. If the two objects move in the same direction with speeds u and v, then
relative speed = difference of their speeds = u – v.
This is also the speed at which the faster object is either drawing closer to the slower object or moving away from the slower object as the case may be.
3. If the two objects start from A and B with speeds u and v respectively, and after crossing each other take a and b hours to reach B and A respectively, then u : v =
√
b
a
Note: In case of Trains moving in the opposite directions or in the same direction, the total distance required to be traveled before they cross each other completely is equal to the sum of the lengths of the two trains. This distance is covered at the relative speeds of the trains.