Question

A soldier fires a bullet horizontally from a top of a cliff from a velocity of 10m/s. If the bullet strikes the ground after 2 second. find the height of the cliff. Also calculate the velocity with which the bullet strikes the ground.​

Answer 1

QUESTION:-

A soldier fires a bullet horizontally from a top of a cliff from a velocity of 10m/s. If the bullet strikes the ground after 2 second. find the height of the cliff. Also calculate the velocity with which the bullet strikes the ground.​

EXPLANATION:-

Using first equation of motion:-

$==> \boxed{\text{v=u+gt}}$

v=final velocity=TO BE CALCULATED

u=initial velocity=10 m/s

g=acceleration due to gravity≈10 m/s²

t=time taken=2 second

$\sf\=> v=u+gt\\\\>v=10+10\times2\\\\>v=10+30\\\\>v=40\;m/s$

So the final velocity(v)=40 m/s

Now let's use 3rd equation of motion to calculate the height of the cliff .

$==>\boxed{\sf{v^2=u^2+2gh}}$

v=Final  velocity=40 m/s

u=initial velocity=10 m/s

g=acceleration due to gravity≈10 m/s

h=height attained= TO BE CALCULATED

$\sf\;>(30)^2=(10)^2+2(10)(h)\\\\>900=100+20h\\\\>900-100=20h\\\\>800=20h\\\\>\frac{800}{20} =h\\\\>40=h\\\\>h=40\;m$

So the height of the cliff is 40 m .