Test: Physical Quantities - Grade 12 MCQ

• The SI consists of 7 base units that describe the 22 units with special names and symbols that are derived. In international trade, the SI plays an important role and is widely used in scientific and technical research and development.
• The modern form of the metric system is the International System of Units (SI). In almost every nation in the world, it is the only method of measurement with official status.
• It consists of a coherent system of measurement units beginning with seven base units, the second (unit of time with the symbol s), the meter (length m), the kilogram (mass, kg), the ampere (electric current, A), the kelvin (thermodynamic temperature, K), the mole (substance quantity, mol) and the candela(luminous intensity, cd).

Important Points

• Escape velocity is the lowest velocity which a body must have to escape the gravitational attraction of a particular planet or other objects.
• The escape velocity of Earth is 11.19 kilometre per second.
• The escape velocity of Venus is 10.36 km per second.
• The escape velocity of Mars is 5.03 km per second.
• The escape velocity of Saturn is 36.09 km per second.

Momentum is a vector quantity.

• In Newtonian mechanics, momentum is the product of the mass and velocity of an object.
  • It possesses a magnitude and a direction. 
  • It is used to describe the state of motion of an object with a non-zero mass.

Vector quantity

• ​The quantity has both magnitudes as well as directions.
• A vector quantity is specified by a number with a unit and its direction
• Some vector quantities are Velocity, acceleration, force, displacement, momentum, electric field, weight, etc.

Scalar quantity

• The quantity only has magnitude but not direction.
• A scalar quantity can be specified by a single number, along with the proper unit.
• Examples: Mass, volume, density, time, temperature, electric current, distance, Energy, speed, etc.

The Correct Answer is Velocity.

• The physical quantities which are specified with the magnitude or size alone are called scalar quantities. For example, length, speed, work, mass, distance, entropy, energy, etc.
• Vector quantities refer to the physical quantities characterized by the presence of both magnitude and direction. For example, velocity, displacement, force, torque, momentum, acceleration, etc.

• A Coulomb is defined as the amount of electric charge transported by one ampere current in one second from one point to another..
• Columb is used to measure the amount of Electric charge.  
• Electric charge: 
  • Electric charge is a general property of protons, electrons, and subatomic particles.
  • Protons are positively charged while electrons are negatively charged.
  • Similar charges repel each other whereas opposite charges attract each other.

• The speed of an object is the amount of the change of its position; thus, it is a scalar quantity.
• The average speed of an object in an interval of time is the distance travelled by an object measured by the length of the interval; the instantaneous speed is the limit of the average speed as the period of the time interval reaches zero.
• Speed has the dimension of the distance separated by time.
• The SI unit of speed is meter per second.

• The SI consists of 7 base units that describe the 22 units with special names and symbols that are derived. In international trade, the SI plays an important role and is widely used in scientific and technical research and development.
• The modern form of the metric system is the International System of Units (SI). In almost every nation in the world, it is the only method of measurement with official status.
• It consists of a coherent system of measurement units beginning with seven base units, the second (unit of time with the symbol s), the meter (length m), the kilogram (mass, kg), the ampere (electric current, A), the kelvin (thermodynamic temperature, K), the mole (substance quantity, mol) and the candela(luminous intensity, cd).

• Thrust is defined as the force acting perpendicular to the surface of an object.
• The formula of thrust
• Thrust = Pressure * Area

Concept

• Resistance: The property of any conductor that opposes the flow of electric current through it is called resistance.
• It is denoted by R and the SI unit is the ohm (Ω).

Explanation:

As explained above, Ohm is the unit of resistance. Named after German physicist Georg Simon Ohm.

• Volt is the unit for electric potential.
• Ampere is the unit for electric current and Joules is the unit for energy.

 Hence option 3 is correct among all

The correct answer is Option 2, i.e 10 ohm.

• Given that two resistors of 20 ohms are connected in parallel.
• So, the resultant resistance
• 1/R_c = 1/R₁ +1/R₂ = 1/20 + 1/20 = 1/10 ohm
• So, R_c = 10 ohm
• A voltage source offers very minimal resistance. Hence, the total resistance is 10 ohms.