Advertisements
Advertisements
प्रश्न
A person of mass 60 kg wants to lose 5kg by going up and down a 10 m high stairs. Assume he burns twice as much fat while going up than coming down. If 1 kg of fat is burnt on expending 7000 kilo calories, how many times must he go up and down to reduce his weight by 5 kg?
Advertisements
उत्तर
Given, the height of the stair = h = 10 m
The energy produced by burning 1 kg of fat = 7000 cal
∴ The energy produced by burning 5 kg of fat = 5 × 7000 = 35000 kcal
35 × 106 cal
The energy utilised in going up and down one time
= `mgh + 1/2 mgh`
= `3/2 mgh`
= `3/2 xx 60 xx 10 xx 10`
= 9000 J
= `9000/4.2`
= `3000/1.4` cal
∴ A number of times, the person has to go up and down the stairs
= `(35 xx 10^6)/(3000/1.4)`
= `(35 xx 1.4 xx 10^6)/3000`
= 16.3 × 103 times
APPEARS IN
संबंधित प्रश्न
Explain why Two bodies at different temperatures T1 and T2, if brought in thermal contact, do not necessarily settle to the mean temperature (T1 + T2)/2.
In changing the state of a gas adiabatically from an equilibrium state A to another equilibrium state B, an amount of work equal to 22.3 J is done on the system. If the gas is taken from state A to B via a process in which the net heat absorbed by the system is 9.35 cal, how much is the net work done by the system in the latter case? (Take 1 cal = 4.19 J)
A force F is applied on a block of mass M. The block is displaced through a distance d in the direction of the force. What is the work done by the force on the block? Does the internal energy change because of this work?
Consider two processes on a system as shown in figure.
The volumes in the initial states are the same in the two processes and the volumes in the final states are also the same. Let ∆W1 and ∆W2 be the work done by the system in the processes A and B respectively.
A gas is contained in a metallic cylinder fitted with a piston. The piston is suddenly moved in to compress the gas and is maintained at this position. As time passes the pressure of the gas in the cylinder ______________ .
A gas is taken through a cyclic process ABCA as shown in figure. If 2.4 cal of heat is given in the process, what is the value of J ?
A gas is taken along the path AB as shown in figure. If 70 cal of heat is extracted from the gas in the process, calculate the change in the internal energy of the system.
A system releases 130 kJ of heat while 109 kJ of work is done on the system. Calculate the change in internal energy.
Which of the following is correct, when the energy is transferred to a system from its environment?
Which of the following system freely allows the exchange of energy and matter with its environment?
derive the relation between the change in internal energy (∆U), work is done (W), and heat (Q).
Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following:
What is the final pressure of the gas in A and B?
In insulated systems, the amount of external work done by the gas is proportional to:
In thermodynamics, heat and work are ______.
If a gas is compressed adiabatically:
The internal energy of one mole of argon is ______.
Explain the change in internal energy of a thermodynamic system (the gas) by heating it.
