Question

Q. 7: if a body increases its velocity with the rate of change of velocity is 7 km/h square from 10 km/h. What is the final velocity of body after 3h.​

Answer 1

By using first equation of motion:

Provided that:

• Acceleration = 7 kmph sq.
• Initial velocity = 10 kmph
• Time = 3 hours

To calculate:

• The final velocity

Solution:

• The final velocity = 31 kmph

Using concept:

• First equation of motion

Using formula:

${\small{\underline{\boxed{\pmb{\sf{\longmapsto \: v \: = u \: + at}}}}}}$

Where, a denotes acceleration, u denotes initial velocity, v denotes final velocity and t denotes time taken.

Required solution:

${\sf{:\implies v \: = u \: + at}}$

${\sf{:\implies v \: = 10 + 7(3)}}$

${\sf{:\implies v \: = 10 + 21}}$

${\sf{:\implies v \: = 31 \: kmph}}$

${\sf{:\implies Final \: velocity \: = 31 \: kmph}}$

• Henceforth, solved!

___________________

By using acceleration formula:

Provided that:

• Acceleration = 7 kmph sq.
• Initial velocity = 10 kmph
• Time = 3 hours

To calculate:

• The final velocity

Solution:

• The final velocity = 31 kmph

Using concept:

• Acceleration formula

Using formula:

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

Where, a denotes acceleration, u denotes initial velocity, v denotes final velocity and t denotes time taken.

Required solution:

$:\implies \sf Acceleration \: = \dfrac{Change \: in \: velocity}{Time \: taken} \\ \\ :\implies \sf a \: = \dfrac{v-u}{t} \\ \\ :\implies \sf 7 \: = \dfrac{v-10}{3} \\ \\ :\implies \sf 7 \times 3 = v - 10 \\ \\ :\implies \sf 21 = v - 10 \\ \\ :\implies \sf 21 + 10 = v \\ \\ :\implies \sf 31 = v \\ \\ :\implies \sf v \: = 31 \: kmph \\ \\ :\implies \sf Final \: velocity \: = 31 \: kmph$