Question

Car starts from rest and achives a speed of 54km/h in 3 second .find its acclertion

Answer 1

Provided that:

• Initial velocity = 0 m/s
• Final velocity = 54 km/h
• Time = 3 seconds

To calculate:

• The acceleration

Solution:

• The acceleration = 5 m/s sq.

Using concepts:

• Formula to convert kmph-mps
• Acceleration formula

Using formulas:

• ${\small{\underline{\boxed{\pmb{\sf{a \: = \dfrac{v-u}{t}}}}}}}$

• ${\small{\underline{\boxed{\pmb{\sf{1 \: kmph \: = \dfrac{5}{18} \: mps}}}}}}$

Where, a denotes acceleration, u denotes initial velocity, v denotes final velocity, kmph denotes kilometre per hour, mps denotes metre per second and t denotes the time taken.

Required solution:

~ Firstly let us convert kmph-mps!

$:\implies \sf 54 \times \dfrac{5}{18} \\ \\ :\implies \sf \cancel{54} \times \cancel{\dfrac{5}{18}} \\ \\ :\implies \sf 3 \times 5 \\ \\ :\implies \sf 15 \: mps \\ \\ {\pmb{\sf{Henceforth, \: converted!}}}$

~ Now finding acceleration!

$:\implies \sf a \: = \dfrac{v-u}{t} \\ \\ :\implies \sf a \: = \dfrac{15-0}{3} \\ \\ :\implies \sf a \: = \dfrac{15}{3} \\ \\ :\implies \sf a \: = 5 \: ms^{-2} \\ \\ :\implies \sf Acceleration \: = 5 \: ms^{-2}$

Answer 2

Answer:-

• Initial velocity=u=0m/s
• Final velocity=v=54km/h

Convert to m/s

$\\ \sf\longmapsto 54\times \dfrac{5}{18}=15m/s$

• Time=t=3s

We know that

$\boxed{\sf Acceleration=\dfrac{v-u}{t}}$

$\\ \sf\longmapsto Acceleration=\dfrac{15-0}{2}$

$\\ \sf\longmapsto Acceleration=\dfrac{15}{2}$

$\\ \sf\longmapsto Acceleration=7.5m/s^2$