JEE MAIN - Physics (2008 - No. 30)
An athlete in the olympic games covers a distance of $$100$$ $$m$$ in $$10$$ $$s.$$ His kinetic energy can be estimated to be in the range
$$200J-500J$$
$$2 \times {10^5}J - 3 \times {10^5}J$$
$$20,000J - 50,000J$$
$$2,000J - 5,000J$$
설명
The average speed of the athelete
$$v = {{100} \over {10}} = 10m/s\,\,\,\,$$ $$\therefore$$ $$K.E. = {1 \over 2}m{v^2}$$
If mass of athlete is $$40$$ $$kg$$ then, $$K.E.$$ $$ = {1 \over 2} \times 40 \times {\left( {10} \right)^2} = 2000J$$
If mass of athlete is $$100$$ $$kg$$ then, $$K.E.$$ $$ = {1 \over 2} \times 100 \times {\left( {10} \right)^2} = 5000J$$
His kinetic energy can be in the range = 2000 J to 5000 J.
$$v = {{100} \over {10}} = 10m/s\,\,\,\,$$ $$\therefore$$ $$K.E. = {1 \over 2}m{v^2}$$
If mass of athlete is $$40$$ $$kg$$ then, $$K.E.$$ $$ = {1 \over 2} \times 40 \times {\left( {10} \right)^2} = 2000J$$
If mass of athlete is $$100$$ $$kg$$ then, $$K.E.$$ $$ = {1 \over 2} \times 100 \times {\left( {10} \right)^2} = 5000J$$
His kinetic energy can be in the range = 2000 J to 5000 J.