Basic Science and Engineering MCQ Quiz - Objective Question with Answer for Basic Science and Engineering - Download Free PDF

Explanation:

Engineering drawing lines:

• Continuous thin lines: these thin continuous lines could be a straight or curved lines. these lines are used for various representations like projection lines, hatching lines, construction lines, short lines, short center lines, measurement lines, dimension lines, intersection lines, lead lines, backside lines.

Additional Information

Concept:

In modern engineering, the materials used have become so numerous and diversified that it is not possible to prescribe different hatching lines for different materials. 

Following are some conventional representation which is used for the  materials:

Explanation:

Mini drafter

• It is an important device used for making drawings quickly & accurately.
• This instrument has a combination of T-square, set-square, protractor, and scales, it helps to draw the drawings at a faster rate. 
• They come in different sizes and a pattern called ‘Pantagraph’ type.
• It is fitted on the top left side, edge of the drafting board, mounted on an adjustable frame or table.

Erasing shield:

• When, on a drawing, if a part of a line or some lines among many other lines needs to be erased or modified, in the normal way of erasing will damage the other nearby lines.
• In such a situation an erasing shield is effectively useful.
• It is a thin metallic sheet having small openings of different sizes and shapes.
• A suitable opening is aligned to the line to be erased and the line is removed by the eraser.

Explanation:

In lifting machines:

• Velocity Ratio (VR) = Distance moved by effort / Distance moved by load

• Mechanical Advantage (MA) = Load lifted / Effort applied

Calculation:

Given:

•  distance moved by effort = 20 m

• distance moved by load = 0.8 m

• Load = 10,000 N

• Effort = 500 N

Velocity Ratio (VR) = 20/0.8 = 25

Mechanical Advantage (MA) = 10000/500 = 20

Explanation:

Dimensions in "mm" for different sizes of drawing sheets are as follows:

The correct answer is the Basic input/output system.

Important Points

• It is the program a personal computer's microprocessor uses to get the computer system started after you turn it on.

Given

Distance1 = 15 km, Speed1 = 30 km/h

Distance2 = 25 km, Speed2 = 10 km/h

Formula Used:

Speed = Distance/Time

Average speed = Total distance/Total time

Calculation:

According to the question,

Total distance = 15 + 25 = 40 km

Total time = 15/30 + 25/10

⇒ (15 + 75)/30 = 90/30 = 3 hours

Average speed = 40/3 km/h

∴ The average speed for the entire journey is 40/3 km/h.

Given 

D₁ = 15 km, S₁ = 30 km/h

D₂ = 25 km, S₂ = 10 km/h

Formula Used:

Average speed = \(\frac{{{D_1} + {D_2}}}{{\frac{{{D_1}}}{{{S_1}}} + \frac{{{D_2}}}{{{S_2}}}}}\)

Calculation:

Average speed for the entire journey = \(\frac{{15 + 25}}{{\frac{{15}}{{30}} + \frac{{25}}{{10}}}}\)

\(= \frac{{40}}{{0.5 + 2.5}}\)

Explanation:

• A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum, used to transfer a force to a load and usually to provide a mechanical advantage.
• On the basis of the locations of fulcrum, load, and effort, the lever is divided into three types.
• First Class Lever:In a first-class lever, the fulcrum is located between the effort and the load. When force is applied to one end of the lever (effort arm), it causes the other end to move, exerting force on the load. Examples include seesaws, crowbars, and scissors.

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• Second-class lever: In a second-class lever, the load is located between the fulcrum and the effort. This means that the effort arm is always longer than the load arm. When force is applied to the effort arm, it causes the load to move. Examples include wheelbarrows, bottle openers, and nutcrackers.

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• Third-class lever: In a third-class lever, the effort is applied between the fulcrum and the load. This means that the load arm is always longer than the effort arm. While third-class levers don't provide a mechanical advantage like first and second-class levers, they allow for greater speed and range of motion. Examples include fishing rods, shovels, and tweezers.

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The derived SI unit of illuminance is the lux (lx).

• It is a type of air pollutant.
• It is derived from vehicular emission from internal combustion engines and industrial fumes that react in the atmosphere with sunlight to form secondary pollutants.
• In certain cities, such as Delhi, smog severity is often increased by stubble burning in neighboring agricultural areas.
• It is highly toxic to humans and can cause severe sickness, shortened life or death.

Explanation: 

If the removal of effort while lifting, results in lowering of the load, the machine is said to be reversible.

The machine is said to be self-locking if the load is not lowered on the removal of the effort.

Important Points

A lifting machine is reversible if its efficiency is greater than 50 per cent and self-locking if its efficiency is less than 50 per cent.

The correct answer is joule.

• The unit of heat in the SI system is Joule.
  • A unit of energy equal to the work done when a force of one newton acts through a distance of one meter.

Important Points

• The other common units for heat are-
  • BTU (Btu) - British Thermal Unit - also known as a "heat unit" in the United States.
  • Calorie: The amount of heat required to raise the temperature of one gram of water 1^oC.
• Erg is a unit of energy.
  • It equal to the force of one dyne over a distance of one centimeter.
  • 1 erg = 10^-7 joule.
• Watt is a unit (SI) of power.
  • It is equal to one joule of work performed per second.
  • 1 horsepower = 746 watt 

Key Points

• 1 joule = 0.14 calorie = 9.478 x 10^-4 Btu.
• 4.184 joule of heat energy (or one calorie) is required to raise the temperature of a unit weight (1 g) of water from 0^oC to 1oC, or from 32^oF to 33.8^oF.
• 1 dyne = 0.00001 newton.

The correct answer is 120-degree.

Key Points

• Draw horizontal and vertical lines to represent an isometric object.
• While horizontal lines are drawn at a 30-degree angle to the horizontal plane, vertical lines remain vertical.
• All three axes must be at a 120-degree angle from one another. Now, if you adhere to rule number 1, this is accomplished automatically.
• An object's three faces are all equally foreshortened in the isometric projection.
• Any mechanical drawing or system is typically explained with an isometric drawing.
• It can be found on instructions for model kits like Lego, Gundam, and others, as well as mechanical infographics. 

Key Points

• In Class 1 and Class 3 levers, the fulcrum or the force is located at one end, requiring support like a bearing or pivot to hold the beam in place.
• Class 1 lever has the fulcrum between the effort and the load (e.g., seesaw), which must be held with a pivot/bearing.
• Class 3 lever has the effort between the fulcrum and the load (e.g., tweezers), also requiring support to stabilize the beam.
• These types of levers need a fixed point or axis of rotation, which is typically provided by a bearing, hinge, or other support.
• Class 2 levers do not usually require a bearing to stabilize the beam in the same way, as the load lies between the effort and fulcrum (e.g., wheelbarrow).

Additional Information

• Class 1 Lever:
  • Fulcrum between load and effort.
  • Examples: Seesaw, scissors, crowbar.
  • Can multiply force or speed depending on fulcrum position.
• Class 2 Lever:
  • Load between effort and fulcrum.
  • Examples: Wheelbarrow, nutcracker.
  • Always multiplies force; mechanical advantage > 1.
• Class 3 Lever:
  • Effort between fulcrum and load.
  • Examples: Tweezers, tongs, human forearm.
  • Multiplies speed and distance; mechanical advantage < 1.
• Role of Bearings:
  • Bearings provide rotational support to the lever beam, minimizing friction.
  • Essential in systems where a stable pivot point is necessary.
• Mechanical Advantage:
  • Levers provide mechanical advantage by trading force for distance or vice versa.

• The greenhouse effect occurs when Earth's atmosphere traps solar radiation because of the presence of certain gases called green house gases.
• This results in an overall increase in the average temperature of the earth’s atmosphere.
• Some major greenhouse gases are- Carbon dioxide, Methane, Nitrous oxide, Chlorofluorocarbons, etc.