Question

velocity of a body of mass 20kg decreases from 20 metre per second to 15 metre per second in a distance of 12.5 metres deceleration of the body is​

Answer 1

Answer:

Initial velocity (u) = 20m/s

Final velocity (v) = 5m/s

Distance travelled (s) = 100m

Using the 3rd equation of motion,

v² - u² = 2as where a is the acceleration

5² - 20² = 2a (100)

25 - 400 = 200a

- 375 = 200a

a = - 375 / 200 = - 1.875

So, the acceleration is - 1.875 m/s²

Now,

Force = mass × acceleration

= 20 kg × (- 1.875) m / s²

= -37.5 kgm/s²

= -37.5 N

(negative sign indicates that the force is opposite to the direction of motion.)

Therefore, the force on the body is - 37.5 N

Explanation:

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Answer 2

$\underline{\huge\mathbb{GIVEN :-}}$

$\longmapsto \color{purple} {Mass\ of\ a\ body\ is\ 20\ kg.}$

$\longmapsto \color{purple} {Velocity\ of\ the\ body\ decreases\ from\ 20\ m/s\ to\ 15\ m/s.}$

$\longmapsto \color{purple} {The\ body\ travels\ a\ distance\ of\ 12.5\ m.}$

$\underline{\bold{\mathbb{TO\ FIND :-}}}$

$\color{orange} {The\ deceleration(or\ retardation)\ of\ the\ body.}$

$\underline{\mathbb{SOLUTION:-}}$

$\color{aqua} {Initial\ velocity(u)=20\ m/s}$

$\color{aqua} {Final\ velocity(v)=15\ m/s}$

$\color{aqua} {Distance\ travelled(s)=12.5\ m}$

$\color{aqua} {We\ know,}$

$\small\boxed{\color{black} {v^2-u^2=2as}}$

$\color{aqua} {Substituting\ the\ known\ values :}$

$\color{black} {15^2-20^2=2\times a\times12.5}$

$\color{black} {\implies 225-400=25a}$

$\color{black} {\implies -175=25a}$

$\color{black} {\implies a=\frac{-175}{25}}$

$\large\underline{\boxed{\color{black} {\implies a=-7\ m/s^2}}}$

$\underline{\color{aqua} {\therefore So,\ the\ deceleration\ of\ the\ body\ is\ 7\ m/s^2.}}$