Question

9 A5 kg sphere is projected vertically upward with a speed of 20 ms' It rises to a height of 12 m. The energy used up in overcoming the air resistance is​

Answer 1

Answer:

Conservation of energy is the best way to solve these type of problems.

The ball initially only has kinetic energy =

KE=12mv2=12(5)(20)2=1000JKE=12mv2=12(5)(20)2=1000J

The kinetic energy is converted to potential energy and energy used in overcoming air resistance:

KE=PE+EfricKE=PE+Efric

or

12mv2=mgh+Efric12mv2=mgh+Efric

or

1000Nm=(5)(9.81)(12)+Efric1000Nm=(5)(9.81)(12)+Efric

EfricEfric=411J