Question

If a car at rest accelerates uniformly to a speed of 144 km/hr in 20 sec,it covers a distance of,.
a.1440 cm
b.2980 cm
c.20 m
d.400 m.​

Answer 1

Explanation:

400

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Answer 2

$\huge {\orange {\bf {\underline {\underline {AnSwer}}}:-}}$

If a car at rest accelerates uniformly to a speed of 144 km/hr in 20 sec,it covers a distance of,.

a) 1440 cm

b) 2980 cm

c) 20 m

☑ d) 400 m.

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Explaination :-

➝ Given :-

• Initial velocity = u = 0 m/s
• Final velocity = v = 144 km/hr

⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀= 144×5/18 = 40m/s

• Time taken = t = 20 seconds

➝ To find :-

Distance covered by the car

➝ Solution :-

First using the first equation of motion:

$\longrightarrow \sf v = u + at$

$\longrightarrow \sf 40 = 0 + a × 20$

$\longrightarrow \sf 40 = 20a$

$\longrightarrow \sf a = \cancel \frac{40}{20}$

$\longrightarrow \sf a = 2{ms}^{-2}$

Using the second equation of motion:

$\longrightarrow\sf S = ut + \frac{1}{2}at²$

$\longrightarrow \sf S = 0 × 20 + \frac{1}{2}×2×20²$

$\longrightarrow \sf S = 0 + 1 × 400$

$\bold {\longrightarrow \boxed {\sf S = 400m}}$

The distance covered by the car is equal to 400 metres

Thus, option (d) is the right answer