Answer: µ=0.205
Explanation:
The horizontal forces acting on the ladder are the friction(f) at the floor and the normal force (Fw) at the wall. For horizontal equilibrium,
f=Fw
The sum of the moments about the base of the ladder Is 0
ΣM = 0 = Fw*L*sin74.3º - (25.8kg*(L/2) + 67.08kg*0.82L)*cos74.3º*9.8m/s²
Note that it doesn't matter WHAT the length of the ladder is -- it cancels.
Solve this for Fw.
0= 0.9637FwL - (67.91L)2.652
Fw=180.1/0.9637
Fw=186.87N
f=186.81N
Since Fw=f
We know Fw, so we know f.
But f = µ*Fn
where Fn is the normal force at the floor --
Fn = (25.8 + 67.08)kg * 9.8m/s² =
910.22N
so
µ = f / Fn
186.81/910.22
µ= 0.205
Explanation:
For example, when a drum is struck, the flexible skin (sometimes called a membrane) of the drum vibrates. The compression and expansion of the air on either side of the vibrating membrane produces differences in air pressure. The pressure differences generate a sound wave that propagates outward from the drum surface.
They discovered a vaccine to reduce illnesses, specifically Polio and Influenza. The work of Salk and Sabin has almost eradicated what was once a deadly disesase ( polio) . For example, there were 350,000 deaths related to poliovirus across the world in 1988 and they reduced to 22 in 2017. Also, their work has saved millions of lives from polio induced paralysis
Answer:
The correct answers to the question are
The following statements about neurons are NOT true
A. The resting membrane potential is generally in the range of -40 mv to -75 mv.
C. Neurons repolarize by opening chloride channels on the membrane.
D. An action potential can occur when the neuron's sodium gates open.
Explanation:
A. The resting membrane potential is generally in the range of -40 mv to -75 mv.
Not true the resting potential for neurons range from -70 to -80 mv
B. Maintaining resting membrane potential requires the use of energy from ATP True
The potential of the membrane arises from the splitting of potassium ions from the intracellular anions by agents powered by ATP
C. Neurons repolarize by opening chloride channels on the membrane
Not True
Repolarization occurs by the outward transit of the positively charged K⁺ from the cell
D. An action potential can occur when the neuron's sodium gates open.
Not True
An action potential takes place once the neuron transmits information along an axon. An action potential results when different ions pass through the membrane of the neuron
Where the displacement is a maximum the pressure is a minimum.
Where the displacement is zero, the pressure is a maximum.
