Question

An adult weighing 600 N raises the centre of gravity of his body by 0.25 m while taking each step of 1 m length in jogging. If he jogs for 6 km, the energy utilized by him in jogging is:

• A. $9 \times 10 ^ { 6 }$J
• B. $9 \times 10 ^ { 5 }$J
• C. $6 \times 10 ^ { 6 }$J
• D. $6 \times 10 ^ { 5 }$ J

Answer 1

Answer: (B)

$9 \times 10 ^ { 5 }$J

Answer 2

Here, mg = 600 N

H = 0.25 m

Length of each step = 1 m

$\therefore$No of steps in 6 km is

$\mathrm { N } = \frac { 6 \times 10 ^ { 3 } \mathrm {~m} } { 1 \mathrm {~m} } = 6000$

$\therefore$energy utilized in jogging is

E = Nmgh = 6000 × 600N × 0.25 m

$= 9 \times 10 ^ { 5 } \mathrm {~J}$