# General Engineering and Applied Sciences Mastery Test 1: ECE Pre-Board

(Last Updated On: January 7, 2018)

26. Block A, with mass mA, is initially at rest on a horizontal floor. Block B, with mass mB, is initially at rest on the horizontal top surface of A. The coefficient of static friction between the two blocks is µs. Block A is pulled with a horizontal force. It begins to slide out from under B if the force is greater than:

• A. mAg
• B. mBg
• C. µsmAg
• D. µs (mA +mB)g

Solution:

27. A distinct legal entity which can practically transact any business transaction which a real person could do.

• A. sole proprietorship
• B. enterprise
• C. partnership
• D. corporation

Solution:

28. An example of an inertial reference frame is

• A. any reference frame that is not accelerating
• B. a frame attached to a particle on which there are no forces
• C. any reference frame that is at rest
• D. a reference frame attached to the center of the universe

Solution:

29. An object moving in a circle at constant speed

• A. must have only one force acting on it
• B. is not accelerating
• C. is held to its path by centrifugal force
• D. has an acceleration of constant magnitude

Solution:

30. The boundary line between (liquid + solid) and (solid) regions must be part of

• A. Solvus
• B. Solidus
• C. Liquidus
• D. Tie-line

Solution:

31. A 50-N force is the only force on a 2-kg object that starts from rest. When the force has been acting for 2-s the rate at which it is doing work is

• A. 75 W
• B. 100 W
• C. 1000 W
• D. 2500 W

Solution:

32. A disk is free to rotate on a fixed axis. A force of given magnitude F, in the plane of the disk, is to be applied. Of the following alternatives the greatest angular acceleration is obtained if the force is

• A. applied tangentially halfway between the axis and the rim
• B. applied tangentially at the rim
• C. applied radially halfway between the axis and the rim
• D. applied radially at the rim

Solution:

33. A cylinder is 0.10 m in radius and 0.20 m in length. Its rotational inertia, about the cylinder axis on which it is mounted, is 0.020 kg · m2. A string is wound around the cylinder and pulled with a force of 1.0 N. The angular acceleration of the cylinder is

Solution:

34. Figure-out the odd point in the following

• A. Proportional limit
• B. Elastic limit
• C. Yield point
• D. Fracture point

Solution:

35. Two supports, made of the same material and initially of equal length, are 2.0 m apart. A stiff board with a length of 4.0 m and a mass of 10 kg is placed on the supports, with one support at the left end and the other at the midpoint. A block is placed on the board a distance of 0.50 m from the left end. As a result the board is horizontal. The mass of the block is

• A. zero
• B. 2.3 kg
• C. 6.6 kg
• D. 20 kg

Solution:

36. The bulk modulus is a proportionality constant that relates the pressure acting on an object to

• A. the shear
• B. the fractional change in volume
• C. the fractional change in length
• D. Young’s modulus

Solution:

37. Fahrenheit and Kelvin scales agree numerically at a reading of

• A. -40
• B. 0
• C. 273
• D. 574

Solution:

38. If the molecules in a tank of hydrogen have the same rms speed as the molecules in a tank of oxygen, we may be sure that

• A. the pressures are the same
• B. the hydrogen is at the higher temperature
• C. the hydrogen is at the greater pressure
• D. the oxygen is at the higher temperature

Solution:

39. Capitalized cost of any structure or property is equal to

• A. first cost + interest
• B. annual cost of the first cost
• C. first cost + cost of perpetual maintenance, operation and replacement
• D. first cost + salvage value

Solution:

40. A 40-cm long string, with one end clamped and the other free to move transversely, is vibrating in its fundamental standing wave mode. The wavelength of the constituent travelling waves is

• A. 10 cm
• B. 20 cm
• C. 40 cm
• D. 160 cm

Solution:

41. A sample of argon gas (molar mass 40 g) is at four times the absolute temperature of a sample of hydrogen gas (molar mass 2 g). The ratio of the rms speed of the argon molecules to that of the hydrogen is

• A. 1
• B. 5
• C. 1/5
• D. √5

Solution:

42. The rotational inertia of a solid uniform sphere about a diameter is 2/5 MR2, where M is its mass and R is its radius. If the sphere is pivoted about an axis that is tangent to its surface, its rotational inertia is:

• A. MR2
• B. 2/5 MR2
• C. 3/5 MR2
• D. 7/5 MR2

Solution:

43. Young’s modulus is a proportionality constant that relates the force per unit area applied perpendicularly at the surface of an object to

• A. the shear
• B. the fractional change in volume
• C. the fractional change in length
• D. the pressure

Solution:

44. One piston in a hydraulic lift has an area that is twice the area of the other. When the pressure at the smaller piston is increased by Δp the pressure at the larger piston

• A. increases by 2Δp
• B. increases by Δp/2
• C. increases by Δp
• D. increases by 4Δp

Solution:

45. An insulated container, filled with water, contains a thermometer and a paddle wheel. The paddle wheel can be rotated by an external source. This apparatus can be used to determine

• A. specific heat of water
• B. relation between kinetic energy and absolute temperature
• C. efficiency of changing work into heat
• D. mechanical equivalent of heat

Solution:

46. If two objects are in thermal equilibrium with each other:

• A. they cannot be moving
• B. they cannot be undergoing an elastic collision
• C. they cannot have different pressures
• D. they cannot be at different temperatures

Solution:

47. Take the mechanical equivalent of heat as 4 J/cal. A 10-g bullet moving at 2000 m/s plunges into 1 kg of paraffin wax (specific heat 0.7 cal/g·C°). The wax was initially at 20° C. Assuming that all the bullet’s energy heats the wax, its final temperature (in °C) is

• A. 20.14
• B. 23.5
• C. 20.006
• D. 27.1

Solution:

48. The flow back of profit plus depreciation from a given project is called

• A. capital recovery
• B. cash flow
• C. economic return
• D. earning value

Solution:

49. A stone is tied to a string and whirled at constant speed in a horizontal circle. The speed is then doubled without changing the length of the string. Afterward the magnitude of the acceleration of the stone is:

• A. the same
• B. twice as great
• C. four times as great
• D. half as great

Solution:

50. A disk with a rotational inertia of 5.0 kg·m2 and a radius of 0.25 m rotates on a fixed axis perpendicular to the disk and through its center. A force of 2.0 N is applied tangentially to the rim. As the disk turns through half a revolution the work done by the force is

• A. 1.6 J
• B. 2.5 J
• C. 6.3 J
• D. 10 J

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