A particle with an initial velocity of 50 m slows at a constant acceleration to 20 ms-1 over a distance of 105 m. How long does it take for the particle to slow down? (a) 2 s (c) 3 s (b)4 s (d)5 s

Respuesta :

Answer:

Time taken, t = 3 s

Explanation:

It is given that,

Initial velocity of the particle, u = 50 m/s

Final velocity, v = 20 m/s

Distance covered, s = 105 m

Firstly we will find the acceleration of the particle. It can be calculated using third equation of motion as :

[tex]v^2-u^2=2as[/tex]

[tex]a=\dfrac{v^2-u^2}{2s}[/tex]

[tex]a=\dfrac{(20\ m/s)^2-(50\ m/s)^2}{2\times 105\ m}[/tex]

[tex]a=-10\ m/s^2[/tex]

So, the particle is decelerating at the rate of 10 m/s². Let t is the time taken for the particle to slow down. Using first equation of motion as :

[tex]t=\dfrac{v-u}{a}[/tex]

[tex]t=\dfrac{20\ m/s-50\ m/s}{-10\ m/s^2}[/tex]

t = 3 s

So, the time taken for the particle to slow down is 3 s. Hence, this is the required solution.