**Speed: -**The rate at which an object travels to cover a certain distance. [Unit - km/hr, m/sec]

**Time: -**The duration spent to cover a certain distance. [Unit - hr, min, sec]

**Distance: -**The length of the path travelled by an object between two places. [Unit – km, m]

### Relationship between Speed, Time & Distance

Speed=

2) 1

Speed=

5 miles= 8 km

So, 10 miles= 16km

speed=

Avg. Speed=

Distance travelled by Raju = 2 ✕35 ✕

Distance travelled by Ravi = 2✕35✕

Example: - Paresh increases his speed by times of his original speed and reaches his office at 20 minutes before the fixed time. Find the usual time taken by him?

^{Distance}/_{Time}#### Note: -

1) Unit of speed, time and distance should be in the same metric system.2) 1

^{km}/_{hr}=^{5m}/_{18s}## Formulas Including Short Tricks:

### Trick 1.

**Calculation of Speed when units are not belong to same metric system –**Speed=

^{Distance}/_{Time}**Example:**- A car covers 10 miles in 4 hrs. Find the speed of the car?5 miles= 8 km

So, 10 miles= 16km

speed=

^{16}/_{4}- 4 km/hr### Trick 2.

**Calculation of distance if speed is constant –**^{D1}/_{T1}=^{D2}/_{T2}**Example:**-A person covers km in 4^{4}/_{7}hrs. What distance will he cover in 7 hrs?### Trick 3.

**Calculation of average speed if certain distance is covered at speed A & same distance is covered at distance B –**Avg. Speed=

^{2AB}/_{A+B}**Example: -**Ruchi covers a distance from her home to school by car at 25 km/hr and she returns back by scooter with a speed of 20 km/hr. Find the average speed for the whole journey?### Trick 4.

**Calculation of distance if two persons travels from point P to Q ( having distance D) with given different speeds and second person reaches point Q first, returns immediately and meet first person at R –****Example: -**If Raju and Ravi travels from P to Q having the distance of 35 km at 8 km/hr and 6 km/hr respectively. Raju reaches Q first and returns immediately & meet Ravi at R. Find the distance travelled by Raju and Ravi?Distance travelled by Raju = 2 ✕35 ✕

^{8}/_{14}= 40 kmDistance travelled by Ravi = 2✕35✕

^{6}/_{14}= 30km### Trick 5.

Calculation of speed if two persons start running at the same time in opposite direction (P & Q) between two points and after passing each other (R), they complete their journey in x and y hr respectively –**Example: -**Richa went out to cycle from P to Q and at the same time Pooja starts to cycle from Q to P. After passing each other, they complete their journey in 16 hrs and 9 hrs respectively. If speed of the Richa is 27 km/hr then what will be the speed of Pooja?### Trick 6.

Calculation of time if a person changes his speed (in fraction such has times) of his original speed and reaches either late or early by t minutes –Example: - Paresh increases his speed by times of his original speed and reaches his office at 20 minutes before the fixed time. Find the usual time taken by him?