Question

Example 4 A 270 m long goods train is
running at 40.5 km/h. How much time
will it take to cross a tree?
(a) 12 s (b) 15 s (c) 24 s (d) 13 s​

Answer 1

Answer:

24 sec

Step-by-step explanation:

40.5*5/18 = 11.25

=270/11.25 = 24 sec

Answer 2

Question :-

A 270 m long goods train is running at 40.5 km/h. How much timewill it take to cross a tree?

(a) 12 s (b) 15 s (c) 24 s (d) 13 s

Answer :-

→ Option (c) is correct { 24 s}

To Find :-

→ Time

Formula used :-

$\boxed{\sf{\red{ speed }\: = \orange{ \frac{distance}{time} } }}$

______________________

Explanation :-

According to the question,

Length of train is 270 m

Speed of train = 40.5 km / hr

Time taken to cross that tree is t = ? ,

$\sf{\orange{firstly \: we \: }\red{have \: to} \: \green{convert \: units} \: from \: \blue{ \frac{km}{hr} }} \\ \sf{to \: \frac{m}{s} } \\ \\ \because \sf{ 1 \: \frac{km}{hr} = \red{ \frac{1000 \: m}{3600 \: s} }} \\ \\ \therefore \sf{ \green{40.5 \: \frac{km}{hr} } = \orange{ \frac{40.5 \times 1000}{3600} } \: \: \frac{m}{s} } \\ \\ \rightarrow \sf{\green{ \frac{40.5 \times 5}{18}} = \frac{405}{36} = 11.25 \: \frac{m}{s} }$

Therefore ,

Using the given formula

$\implies \sf{ 11.25 = \orange{\frac{270}{t} }} \\ \\ \implies \sf{\red{ t \: = \frac{270}{11.25} } }\\ \\ \implies \boxed{\sf{ \green{t \: = 24 \: s}}}$

Hence it take 24 seconds to cross that tree .

_____________________