Analyze the example of this door knob wheel and axle. • The radius of the wheel, or in this case the handle, is 4.125 inches.
• The radius of the axle that opens the latch (inside the mechanism) is 0.125 inch. The actual effort force needed to open the door is 2.25 pounds.
The efficiency of this type of door knob is 85%.
Calculate the ideal mechanical advantage of this wheel and axle system when the resistance force is applied to the axle.
Formula, substitute, final answer

28

Explanation:

Velocity ratio= Radius of wheel/radius of axle

Radius of wheel= 4.125 inches

Radius of axle= 0.125 inches

Velocity ratio = 4.125/0.125 = 33

Then;

Efficiency = mechanical advantage/velocity ratio × 100

Since the efficiency of the system = 85%

85 = mechanical advantage/33 × 100

Mechanical advantage = 85 × 33/100 = 28

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.