Eating 2500 Cal every day a friend of mine maintains a stable weight of 70 kg. One day, after eating 3500 Cal, he decided to do extra exercise to avoid gaining weight. He was doing jumps: he leaves the ground with a speed of 3.3m/s at every jump. Assuming that his body turns energy to mechanical work with a 25 % efficiency, how many jumps he will have to make

2721

Explanation:

First, we find the change in calories

E = E(taken) - E(daily)

E = 3500 - 2500

E = 1000 cal

Next, we use the efficiency to find the available metabolic energy

E' = n.E, where n = efficiency

E' = 0.25 * 1000

E' = 250 cal

Converting this cal to J, we have

1 cal = 4.18 J

250 cal = 250 * 4.18 J

250 cal = 1045 kJ

Given that the final velocity is 0, we use equation of motion to find the height, h attained

u² = 2gh

h = u²/2g

h = 3.3² / 2 * 9.81

h = 10.89 / 19.62

h = 0.56 m

Potential energy, E = mgh

E = 70 * 9.8 * 0.56

E = 384 J

Total number of jumps, n =

n = 1045 / 384

n = 2721 jumps

an electric circuit

i just did an experiment like this in my science class. also the answer is yes, it will get separated because they are two opposites meaning if they are opposite they can not attract.

hope this .!