Tag: energy for everything

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Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

Energy stored in the bonds of molecules is a form of:

  1. heat energy

  2. potential energy'

  3. chemical energy

  4. light energy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Energy that gets released when the bonds are formed was stored in the electromagnetic fields inside of the atom. When the bond is formed, the electrons and protons assume a configuration that has an, overall, less intense combination of electric and magnetic fields inside of the bonded atoms than when they were separate. 

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

A body $A$ is placed on a railway platform and an identical body $B$ in a moving train. Which of the following energies of $B$ are greater than those of $A$ as seen from the ground?

  1. Kinetic

  2. Total

  3. Mechanical

  4. Internal
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Since the body B is in a moving train, it will have higher kinetic energy as compared to the body on platfrom. It is because the speed of the body $A$ is zero.

The total energy of the body $B$ will be more than body $A$ due to its state of motion and the mechanical energy of the body $B$ will be higher due to more amount of work done on it as it is moving.

The internal energy of the two identical bodies do not depend on other external factors and it remains constant for the bodies.

So, only the internal energy will not change.

Multiple choice physics work, energy and power forms of energy and energy conservation energy for everything forms of energy

Geothermal energy is feasible in regions that

  1. Are near the sea

  2. Have thermal plants

  3. Have coal mines

  4. Are over hot spots in the crust
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Geothermal energy relies on heat from the Earth's interior. Regions over hot spots in the crust, where magma is relatively close to the surface, are ideal for tapping into this heat.

Multiple choice physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

A charged parallel plate capacitor of distance ($d$) has ${U} _{0}$ energy. A slab of dielectric constant ($K$) and thickness ($d$) is then introduced between the plates of the capacitor. The new energy of the system is given by:

  1. $K{U} _{0}$
  2. ${K}^{2}{U} _{0}$
  3. $\cfrac{{U} _{0}}{K}$
  4. $\cfrac{{U} _{0}}{{K}^{2}}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a dielectric slab of constant K completely fills the space between the plates of a charged disconnected capacitor, the capacitance increases by a factor of K, becoming C equals K times C0. Since the charge remains constant, the stored energy U equals Q squared divided by 2C, which means the new energy becomes the initial energy divided by K.

Multiple choice physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

 person trying to lose weight by burning fat lifts a mass of $10kg$ upto a height of $0.5\, m\, with\, in\, 1000$ times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies $3.8 \times 10^7 J$ of energy per kg which is converted to mechanical energy with a $20 \%$ efficiency rate. 

  1. $6.45 \times {10^{ - 3}}kg$
  2. $9.89 \times {10^{ - 3}}kg$
  3. $12.89 \times {10^{ - 3}}kg$
  4. $2.45 \times {10^{ - 3}}kg$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Work done per lift = mgh = 10 * 9.8 * 0.5 = 49 J. Total work for 1000 lifts = 49,000 J. With 20% efficiency, energy required from fat = 49,000 / 0.20 = 245,000 J. Fat energy density = 3.8 * 10^7 J/kg. Mass of fat = 245,000 / (3.8 * 10^7) = 6.447 * 10^-3 kg.