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In this exercise we will learn about

**speed and its various types**.Speed

Speed simply tells us how fast an object can move. Speed is the scalar quantity, which only tells the magnitude (numerical value) of how much speed that an object travels.

**or**

Speed is the rate of change of distance.

$\mathit{Speed}=\frac{\mathit{Distance}\phantom{\rule{0.147em}{0ex}}(d)}{\mathit{Time}\phantom{\rule{0.147em}{0ex}}(t)}$

The SI unit of speed is $\frac{\mathit{metre}\phantom{\rule{0.147em}{0ex}}(m)}{\mathit{second}\phantom{\rule{0.147em}{0ex}}(s)}=\frac{m}{s}=m{s}^{-1}$

And, if we want to calculate the distance using speed and time, we can use the following formula,

$\mathit{Distance}\phantom{\rule{0.147em}{0ex}}=\mathit{Speed}\times \mathit{Time}$.

We can classify the speed into two types with respect to distance and time.

**Two types of speed**

- Uniform speed
- Non-uniform speed

**Uniform speed:**

If an object in motion covers equal distances in equal intervals of time, then the object is said to be in uniform speed.

**Non-uniform speed:**

If an object covers unequal distances in equal intervals of time, the object is said to be in non-uniform speed.

**Average speed:**

We can calculate the average speed of an object by dividing the total distance travelled by the object and the total time taken to travel the distance.

That is, $\mathit{Average}\phantom{\rule{0.147em}{0ex}}\mathit{speed}=\frac{\mathit{Total}\phantom{\rule{0.147em}{0ex}}\mathit{distance}\phantom{\rule{0.147em}{0ex}}\mathit{travelled}}{\mathit{Total}\phantom{\rule{0.147em}{0ex}}\mathit{time}\phantom{\rule{0.147em}{0ex}}\mathit{taken}\phantom{\rule{0.147em}{0ex}}\mathit{to}\phantom{\rule{0.147em}{0ex}}\mathit{travel}\phantom{\rule{0.147em}{0ex}}\mathit{the}\phantom{\rule{0.147em}{0ex}}\mathit{distance}}$