chap 3: forces 🙄

Question 1

where does aerodynamic lift act on

Answer 1

direction perpendicular to wing or rotor blade

Question 2

state Hooke’s Law

Answer 2

the change in length of a material is directly proportional to the applied force

Question 3

define upthrust

Answer 3

upward force exerted by a fluid on an object submerged fully or partially in the fluid due to the difference in pressure exerted by the fluid on upper and lower surfaces of the object

Question 4

upthrust is also _____

Answer 4

equal in magnitude and opposite in direction to the weight of the fluid displaced

Question 5

why does an object float

Answer 5

upthrust is equal in magnitude and opposite in direction with the weight of the object

Question 6

why does an object sink

Answer 6

upthrust acting on object is less than the weight

Question 7

definition of moments

Answer 7

product of the force and the perpendicular distance of the point from the line of action of the force

Question 8

what is a couple

Answer 8

1. equal in magnitude & opposite in direction
2. line of action do not coincide

Question 9

definition of torque

Answer 9

product of one of the forces and the perpendicular distance between the forces

Question 10

what are the two conditions that must be satisfied for object to be in equilibrium

Answer 10

1. resultant force = 0
2. resultant torque = 0

Question 11

state the principle of moments

Answer 11

when an object is in equilibrium, the sum of clockwise moment about any point is the same as the sum of anti clockwise moment about the same point