Motion Under Gravity

Question

Sir, i am a student of class 9 and i have a doubt.

The question is.. From the top of a tower of 200m height, a stone is projected vertically upwards with a velocity of 49 m/s.

Calculate the time to reach the ground.

I Did approach the answer through a website .. but i dint understand why the initial velocity (u) was with a negative sign.

Sir.. can u show me the method and the explanations of my doubts,.. Please

Kurma Anudeep · Accepted Answer

let s=200m u=-49m/s a=9.8m/s^2 v^2=u^2+2as =2401+19.6*200 =2401+3920 v=79.5m/s v=u+at 79.5=-49+9.8t 128.5=9.8t t=128.5/9.8=13.11s u is negative because the ball is thrown against the gravitational force ALL THE BEST

General Physics> Motion Under Gravity...

Aditya Pati , 12 Years ago

Kurma Anudeep

Provide a better Answer & Earn Cool Goodies

LIVE ONLINE CLASSES

Ask a Doubt

moment of inertia of a equilateral triangle about an axis passing through centre and perppendicular to the plane

general physics

. Because of the rotation of the earth, a plumb bob may not hang exactly along the direction of
the earth’s gravitational pull (its weight) but deviates slightly from this direction. Calculate the
deviation (a) at 40 latitude, (b) at the poles, and (c) at the equator

general physics

general physics

A block is kept on x-y plane at a point (2m,3m). It is pushed with a force of magnitude 10 Ntowards point (5m,7m). The force can be represented as?

general physics

The phase of particle at t is 70°and another particle is at t is 790° what is wavelength if the distance between two particles is1 m

general physics

General Physics> Motion Under Gravity...

Aditya Pati , 12 Years ago

Kurma Anudeep

Provide a better Answer & Earn Cool Goodies

LIVE ONLINE CLASSES

Ask a Doubt

Other Related Questions on general physics

moment of inertia of a equilateral triangle about an axis passing through centre and perppendicular to the plane

general physics

. Because of the rotation of the earth, a plumb bob may not hang exactly along the direction ofthe earth’s gravitational pull (its weight) but deviates slightly from this direction. Calculate thedeviation (a) at 40 latitude, (b) at the poles, and (c) at the equator

general physics

general physics

A block is kept on x-y plane at a point (2m,3m). It is pushed with a force of magnitude 10 Ntowards point (5m,7m). The force can be represented as?

general physics

The phase of particle at t is 70°and another particle is at t is 790° what is wavelength if the distance between two particles is1 m

general physics

. Because of the rotation of the earth, a plumb bob may not hang exactly along the direction of
the earth’s gravitational pull (its weight) but deviates slightly from this direction. Calculate the
deviation (a) at 40 latitude, (b) at the poles, and (c) at the equator