Question

A girl of height 120 cm is walking away from the base of a lamp-post at a speed of 1.2 m/s. If the lamp is 4.8 m above the ground, then find the length of her shadow after 6 s.
(hoping to find the answer soon I'm desperate) ​

Answer 1

Answer: 2.4 m

Explanation:

Distance of girl from lamp after 6 seconds = 1.2×6 = 7.2 m

120 cm = 1.2 m

Let the length of shadow be x

$\frac{4.8}{7.2+x}=\frac{1.2}{x}$

$\Rightarrow 4.8x=8.64+1.2x$

$\Rightarrow 4.8x-1.2x=3.6x=8.64$

$\Rightarrow x=\frac{8.64}{3.6}=2.4$

The length of shadow is 2.4 m

Hope it helped

Answer 2

Answer:

2.4m

Explanation:

Distance of girl from lamp after 6 seconds = 1.2×6 = 7.2 m

120 cm = 1.2 m

Let the length of shadow be x

\frac{4.8}{7.2+x}=\frac{1.2}{x}

7.2+x

4.8

=

x

1.2

\Rightarrow 4.8x=8.64+1.2x⇒4.8x=8.64+1.2x

\Rightarrow 4.8x-1.2x=3.6x=8.64⇒4.8x−1.2x=3.6x=8.64

\Rightarrow x=\frac{8.64}{3.6}=2.4⇒x=

3.6

8.64

=2.4

The length of shadow is 2.4 m

Hope it helped