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2 years ago

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An object has a mass of 60 kg. It decelerates from 50 m/s to 20 m/s when a resultant force of 300 N acts on it. For how long doe

s the force act?
A 0.071 s
B 0.17 s
C 6.0 s
D 14 s

1 answer:

Pavlova-9 [17]2 years ago

4 0

Force=300N
Mass=60kg

Find Acceleration

$\\ \rm\longmapsto F=ma$

$\\ \rm\longmapsto a=\dfrac{F}{m}$

$\\ \rm\longmapsto a=\dfrac{-300}{60}$

$\\ \rm\longmapsto a=-5m/s^2$

Now

u=50m/s
v=20m/s

Using 1st equation of kinematics

$\\ \rm\longmapsto v=u+at$

$\\ \rm\longmapsto t=\dfrac{v-u}{a}$

$\\ \rm\longmapsto t=\dfrac{20-50}{-5}$

$\\ \rm\longmapsto t=\dfrac{-30}{-5}$

$\\ \rm\longmapsto t=6$

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we can find how far the third drop was when the first drop hits the ground from the formula s = ut + $0.5at^{2}$

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