# Aerodynamics Questions and Answers – Energy Equation

This set of Aerodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Energy Equation”.

1. Conservation of energy is based on which law of thermodynamics?
a) First law of thermodynamics
b) Second law of thermodynamics
c) Zeroth law of thermodynamics
d) Third law of thermodynamics

Explanation: First law of thermodynamics states that energy can neither be created nor be destroyed but it can be converted from one form to another.

2. The kinetic energy of an object depends only on magnitude.
a) True
b) False

Explanation: The kinetic energy depends only on magnitude. Kinetic energy is the product of mass and the square of velocity. The dot product of vector quantity is always scalar, hence it is the scalar quantity and depends only on magnitude.

3. The formula for kinetic energy is __________
a) KE = 0.5*m*v
b) KE = 0.5*m*v2
c) KE = m*v2
d) KE = 0.6*m*v2

Explanation: It is product of mass and square of velocity. Kinetic energy comes in picture in case of moving objects and also for the objects which has certain mass. It is defined as the work needed to accelerate a body from its rest to the moving condition.

4. A body moves 5m in a forward direction and then comes back to the same position. Which of the following energy does it have?
a) Potential energy
b) Sum of kinetic energy plus potential energy
c) Kinetic energy
d) Impulsive energy

Explanation: A moving object always has kinetic energy. When a body will move in a forward direction, it will gain some kinetic energy which will be the product of mass and square of velocity. A body in motion always store kinetic energy in it.

5. The SI unit of kinetic energy is ___________
a) Newton
b) Joules
c) Pascal
d) Meters

Explanation: The formula for kinetic energy is 0.5*m*v2. The dimensional formula for kinetic energy is kg*(m/s)2, which may be defined as 1 joule. 1 joule = kg*m2/s2. 1 Joule is defined as the energy transferred to an object when the force of 1 Newton is acted on a body through a distance of 1 meter.

6. Determine the kinetic energy of the body of mass 90 kg moving with a speed of 200 m/s.
a) 15000 Joules
b) 900000 Joules
c) 21000 Joules
d) 40000 Joules

Explanation: KE=0.5*m*v2.
Substitute the values in the formula.
Here, m=90 kg and v= 200 m/s.
On solving the above equation we get,
KE=0.5*90*(200)2= 900000 Joules.

7. The energy equation, the total energy is equal to the sum of _______
a) Kinetic energy + potential energy
b) Kinetic energy + pressure energy
c) Kinetic energy + potential energy + pressure energy
d) Pressure energy + potential energy

Explanation: The total energy is the sum of kinetic energy plus potential energy plus internal energy. Where kinetic energy is given by 0.5 m*v2 where m is the mass and v is the velocity. Potential energy is given by PE=mgh where, m is the mass, g is the acceleration due to gravity and h is the height. The internal energy is denoted by ‘I’.

8. In a thermodynamic system, the measurement of heat is called as ___________
a) Entropy
b) Enthalpy
c) Internal energy
d) Heat transfer

Explanation: Enthalpy is the total heat content in the system. It is an extensive property and is the sum of internal energy plus the product of pressure and volume.
H = U+ p*V

9. The enthalpy is _____
a) H = U+ p*V
b) H = U+ p
c) H = U+I
d) H = U+ p*V2

Explanation: Enthalpy is the total heat content in a system. ‘H’ is enthalpy, ‘U’ is internal energy, ‘p’ is the pressure and ‘V’ is the volume. Enthalpy is an extensive property. It is equal to the product of internal energy plus the product of pressure and volume.

Sanfoundry Global Education & Learning Series – Aerodynamics.

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