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Power Engineering 4A - Unit 1 -
Elementary Mechanics and Dynamics
Latest Update Graded A+
What is the power required to apply a 200kN force over a distance of 15m in 15 seconds?
Select one:
a. 3000 W
b. 1500 kW
c. 1000 kW
d. 200 kW โโD
A 7m long bar is pivoted at 2m from the left end. A force of 60N is applied downwards on the left end and a force of 20N is applied downward on the right end. What would be the clockwise and counter-clockwise moments about the pivot, due to each force, and in which direction would the bar rotate?
Select one:
a. 120Nm counter-clockwise, 100Nm clockwise, clockwise rotation.
b. 120Nm counter-clockwise, 100Nm clockwise, counter-clockwise rotation.
c. 80Nm counter-clockwise, 100Nm clockwise, counter-clockwise rotation.
d. 60Nm counter-clockwise, 100Nm clockwise, clockwise rotation. โโB
A titanium bar with a mass of 2kg and a length of 3m shortens by 0.02mm under a compressive load of 3900kN. What is the strain?
Select one:
a. 6.66 x 10-
b. -1.9 x 102
c. 0.00000 6666
d. 1.9 x 10- 3 โโC
External tensile forces acting parallel but not in line produce _________ in an object.
Select one:
a. Shear stress
b. Working stress
c. Compressive stress
d. Tensile stress โโA
The ratio between the ultimate strength and the allowable stress is called the:
Select one:
d. 100 kPa โโB
How much work is done by a pump with a 0.1m diameter piston, traveling 250mm against a pressure of 1500kPa?
Select one:
a. 3.72 kJ
b. 5.9 kJ
c. 1.96 kJ
d. 2.95 kJ โโD
The ratio of the load to the effort in a simple machine is called the:
Select one:
a. Velocity ratio
b. Actual mechanical advantage
c. Efficiency
d. Power โโB
Acceleration may be defined as the rate of change of:
Select one:
a. Velocity
b. Displacement
c. Distance
d. Time โโA
The area under a velocity vs. time graph equals:
Select one:
a. Displacement
b. Acceleration
c. Speed
d. Distance โโA
The ability of a material to break without much deformation occurring before fracture is called:
Select one:
a. Hardness
b. Toughness
c. Stiffness
A 28-tooth gear turns at 100 rpm and drives a 112-tooth gear. What is the speed of the follower gear?
Select one:
a. 125.44 rpm
b. 25 rpm
c. 31.36 rpm
d. 400 rpm โโB
If a force of 120kN is exerted uniformly over an area of 0.2 mยฒ, what is the pressure?
Select one:
a. 24 kPa
b. 240 N
c. 60 kPa
d. 600 kPa โโD
'm/s' is the SI unit for:
Select one:
a. Acceleration
b. Velocity
c. Force
d. Mass โโB
Find the coefficient of friction between a 73kg cubic box measuring 3m on each side and a hardwood floor, 16m long and 20m wide, if a force of 236N is required to start the box moving.
Select one:
a. 3.
b. 3.
c. 0.
d. 36 N โโC
If a force of 1400N, applied in the direction of movement, will cause continued steady movement of a 400kg crate. Calculate the coefficient of kinetic friction.
Select one:
a. 0.
b. 3.
c. 5.
A car accelerates uniformly from rest to 6.1 m/s in 40 seconds. It continues at this velocity for an additional 60 seconds. Then it decelerates to a stop in 10 seconds. If the car traveled in a straight line during this time, determine the final distance from its original position.
Select one:
a. 122 m
b. 518.5 m
c. 9.15 m
d. 671 m โโB
Find the force required to move a 25kg block along a horizontal floor if the coefficient of sliding friction is 0.19.
Select one:
a. 46.6 N
b. 4.66 kN
c. 4.28 kN
d. 4.28 N โโA
With static or kinetic friction, the force of friction is proportional to the _______ that presses the two surfaces together.
Select one:
a. Mass
b. Force
c. Energy
d. Pressure โโB
Find the force required to start a 1 tonne object moving along a surface with a coefficient of friction of 0.62.
Select one:
a. 9810 N
b. 6082.2 N
c. 620 N
d. 6.1 N โโB
The input to a 93.33% efficient belt drive system is 75kW. What is the output?
Select one:
a. 70 kW
b. 80.36 kW
Distance is:
Select one:
a. A scalar quantity
b. Measured in a straight line
c. Velocity divided by time
d. Always a vector quantity โโA
A pulley with a diameter of 50cm is driven at 960 r/min. What will be the linear speed, in m/s, of a point on the rim of the pulley?
Select one:
a. 6.
b. 50.
c. 25.
d. 150.8 โโC
A tie bar with a tensile strength of 231MPa carries a load of 11kN. What must be the diameter of the bar if the required factor of safety is 6.
Select one:
a. 114.42 mm
b. 11.4 cm
c. 19.07 mm
d. 19.07 cm โโC
The unit used to indicate acceleration in the SI system is:
Select one:
a. m/s
b. m/s
c. m2/s
d. km/s โโA
Idler gears:
Select one:
a. Increase efficiency.
b. Change the r/min of the driven gear.
c. Create slippage
d. Are used to reverse the direction of the gear rotation. โโD
Select one:
a. Kinetic friction is greater than static friction.
b. Friction is affected by the relative roughness of the two surfaces.
c. Friction force is not affected by the area of the surfaces in contact.
d. Kinetic friction is not affected by a body's speed. โโA
A simple machine is required to raise 1 tonne of stones a vertical distance of 30m. If the efficiency of the pulley is 100%, how much work must be done on the pulley to raise the stone?
Select one:
a. 35 kJ
b. 294.27 kJ
c. 294.3 J
d. 30 kJ โโB
A car travels a total of 350km. The journey involves a total of 3 hours driving time and 45 minutes of stop time. What is the average journey speed?
Select one:
a. 107.7 km/h
b. 116.7 km/h
c. 71.7 km/h
d. 93.3 km/h โโD
For a pivot or lever, the product of force multiplied by a perpendicular distance from the point of rotation, is defined as:
Select one:
a. Potential energy
b. Weight
c. Mass moment
d. Turning moment โโD
A car traveling at 18km/h increases its velocity uniformly to 48km/h in 6 seconds. What is the acceleration in m/sยฒ?
Select one:
a. 1.
b. 1.
c. 1.
d. 1.12 โโB
a. 4
b. 8
c. 1.
d. 6.25 โโA
A 5m long bar is pivoted on the right end and a force of 10N is applied upwards on the left end. The moment of force is:
Select one:
a. 50Nm clockwise
b. 2Nm counter-clockwise
c. 2Nm clockwise
d. 50Nm counter-clockwise โโA
A 1.5m long round bar is 45mm diameter and stretches 1.2mm under a load of 240kN. Calculate the strain in the bar.
Select one:
a. 0.
b. 0.
c. 0.
d. 0.0004 โโc
The "coefficient of friction" is defined as the:
Select one:
a. Force parallel to the surface required to keep an object moving at a constant linear velocity.
b. Reaction perpendicular to the surface.
c. Force parallel to the surface required to start an object moving.
d. Ratio of the force required to move a body to the normal reaction force. โโD
Stiffness is defined as the ability of a material to:
Select one:
a. Resist penetration
b. Resist a change in shape and size when a load is applied
c. Retain its deformed shape when the load causing the deformation is removed
d. Return to its original shape after the load causing deformation is removed โโB
A car travelling at 90km/h is brought to rest over a distance of 120m. What is the average linear acceleration of the car, in m/sยฒ?
