Aprojectile of mass 6.8 kg kg is shot horizontally with an initial speed of 14.5 m/s from a height of 26.7 m above a flat desert surface. the acceleration of gravity is 9.81 m/s². for the instant before the projectile hits the surface, find the work done on the projectile by gravity. answer in units of j.

Explanation:

Given

mass of projectile

initial horizontal speed

height

Considering vertical motion

velocity gained by projectile during 26.7 m motion

v=final velocity

u=initial velocity

a=acceleration

s=displacement

Horizontal velocity will remain same as there is no acceleration

final velocity

Initial kinetic Energy

Final Kinetic Energy

Work done by all the force is equal to change in kinetic Energy of object

Work done by gravity is

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

the entire statement is true and correct.  

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