Answer:
a) 431 Hz
b) 429 Hz
c) 403 Hz
Explanation:
The frequency you heard is calculated using the relation
f = f(s) / [1 - (v(s)/v) ]
f = 400 / [1 - 25/343]
f = 400 / (1 - 0.0729)
f = 400 / 0.9271
f = 431.5 Hz
The frequency your friend starts hearing is
f = f(s) * [1 + (v(s)/v) ]
f = 400 * [1 + 25/343]
f = 400 * (1 + 0.0729)
f = 400 * 1.0729
f = 429.2 Hz
when you're next to each other and you are hearing 3 beats per second. The frequency you're singing is 400 + 3 Hz
403 Hz
Answer:
186 lbs per man.
Explanation:
If we assume that we have 35 men in the elevator, and the elevator will be overloaded if the total weight is in excess of 6510-lbs, so we just need to take average:
6510 lbs / 35 = 186 lbs per man.
Have a nice day!
Answer:
F= 5.71 N
Explanation:
width of door= 0.91 m
door closer torque on door= 5.2 Nm
In order to hold the door in open position we need to exert an equal and opposite torque, to the door closer torque, on the door.
so wee need to exert 5.2 Nm torque on the door.
If we want to apply minimum force to exert the required torque we need to apply force perpendicularly on the door knob (end of door) so that to to greater moment arm.
T= r x F
T= r F sin∅
F= T/ (r * sin∅)
F= 5.2/ (0.91 * 1)
F= 5.71 N
B is the correct answer i guess