Which part of a DC generator keeps the electric current flowing in only one
direction?
A. The permanent magnets
B. The commutator
o
C. The power source
D. The wire coil
1. Some penguins are playing turtle hockey on the frictionless ice. Ramona the penguin hits the turtle
with a force of magnitude F, and the turtle experiences an acceleration of magnitude a (Fand a are of
unknown size). Francisco the penguin hits the same turtle with a force of magnitude three times
greater than Ramona's force (3F). What will the resulting acceleration of the turtle be? Answer in
terms of a. Support your answer with reasoning and reference to Newton's Second Law.
Answer:
a' = 3a
Explanation:
Newton's Second Law gives the magnitude of the unbalanced force applied to an object as follows:
F = ma
where,
F = Force Applied
m = Mass of Object
a = acceleration
FOR RAMONA'S PUSH:
F = F
m = m
a = a
Therefore,
F = ma
a = F/m ---------------- equation (1)
FOR FRANSICO'S PUSH:
F = 3F
m = m (mass of turtle will be same)
a = a'
Therefore,
3F = ma'
a' = 3F/m
using equation 1
a' = 3a
What happens to the minerals as gneiss forms from schist?
Answer:
Explanation:
Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. However, unlike slate and schist, gneiss does not preferentially break along planes of foliation because less than 50% of the minerals formed during the metamorphism are aligned in thin layers.
PLS HELP THIS IS DUE IN TWO HOURS
Answer:
C
Explanation:
What is the Net Force acting
on the box below?
Is Time and Light both connected in anyway?
Answer:
It is not connected by any way
Which of the following is a characteristic of a base?
A. pH greater than 7
B. pH between 4 and 13
C. pH between 4 and 9
D. pH less than 7
Answer:
A. pH greater than 7
Explanation:
Because a base has a pH scale of 8 to 14
An elevator is being pulled up from the ground floor to the third floor by a cable. The cable is exerting 4500 newtons of force on the elevator. According to Newton's law of action-reaction, what is the gravitational force on the elevator, in newtons, if the elevator is NOT accelerating?
Answer:
The gravitational force on the elevator = 4500N
Explanation:
The given parameters are;
The force applied by the elevator, F = 4500 N
The acceleration of the elevator = Not accelerating
From Newton's third law of motion, the action of the cable force is equal to the reaction of the gravitational force on the elevator which is the weight, W and motion of the elevator as follows;
F = W + Mass of elevator × Acceleration of elevator
∴ F = W + Mass of elevator × 0 = W
F = 4500 N = W
The net force on the elevator is F - W = 0
The gravitational force on the elevator = W = 4500N.
The gravitational force on the elevator, if the elevator is NOT accelerating is 4500 N.
Given data:
The magnitude of force on the elevator is, F = 4500 N.
From Newton's third law of motion, the action of the cable force is equal to the reaction of the gravitational force on the elevator which is the weight, W and motion of the elevator as follows,
F = W + ma
Here, a is the acceleration of the elevator. Since, the elevator is not accelerating. Then, a = 0 .
The weight of the elevator is due to the gravitational force. So, we need to obtain the weight as gravitational force.
Solving as,
[tex]F = W+ma\\\\F=W +(m \times 0)\\\\4500=W\\\\W = 4500 \;\rm N[/tex]
Thus, we can conclude that the gravitational force on the elevator, if the elevator is NOT accelerating is 4500 N.
Learn more Newton's third law here:
https://brainly.com/question/17529892
An insulated rigid tank initially contains 1.4-kg saturated liquid water and water vapor at 200°C. At this state, 25 percent of the volume is occupied by liquid water and the rest by vapor. Now an electric resistor placed in the tank is turned on, and the tank is observed to contain saturated water vapor after 20 min. Determine:
(a) the volume of the tank
(b) the final temperature
(c) the electric power rating of the resistor
Solution:
Mass of liquid water and water vapor in the insulated tank initially = 1.4 kg
Temperature = 200 °C
And 25% of the volume by liquid water is steam.
State 1
[tex]$m=\frac{V}{v}$[/tex]
[tex]$m=m_f+m_g$[/tex]
[tex]$1.4=\frac{0.25V}{v_f}+\frac{0.75V}{v_g}$[/tex]
[tex]$1.4=\frac{0.25V}{1.1565 \times 10^{-3}}+\frac{0.75V}{0.1274}$[/tex] (taking the value of [tex]$v_g$[/tex] and [tex]$v_g$[/tex] at 200°C )
[tex]$V=6.304 \times 10^{-3}$[/tex]
Now quality of vapor
[tex]$x=\frac{m_g}{m}$[/tex]
[tex]$=3.377 \times 10^{-3}$[/tex]
Internal energy at state 1 can be found out by
[tex]$u_1=u_f+xu_{fg}$[/tex]
[tex]$=850.65+3.377\times10^{-3}\times 1744.65$[/tex]
= 856.54 kJ/kg
After heating with the resistor for 20 minutes, at state 2, the tank contains saturated water vapor [tex]$v_2=v_g \text { and }\ x=1$[/tex]
Tank is rigid, so volume of tank is constant.
[tex]$v_g=v_2=\frac{V}{m}$[/tex]
[tex]$v_g=\frac{6.304\times 10^{-3}}{1.4}$[/tex]
[tex]$v_g=4.502 \times 10^{-3} \ m^3 /kg$[/tex]
Now interpolate the value to get temperature at state 2 with specific volume value to get final temperature
[tex]$T_2=360+(374.14-360)\left(\frac{0.004502-0.006945}{0.003155-0.006945}\right)$[/tex]
= 369.11° C
Internal energy at state 2
[tex]$u_2=2154.9 \ kJ/kg$[/tex]
Now power rating of the resistor
[tex]$P=\frac{m(u_2-u_1)}{t}$[/tex]
[tex]$P=\frac{1.4(2154.9-856.54)}{20 \times 60}$[/tex]
= 1.51 kW
How do the individual forces compare when the rider experiences a sensation being lighter than his normal weight ? What is the acceleration direction when this occurs ?
Answer:
When the elevator is accelerating downward, the person feels lighter due to the downward normal force being less than the person's weight.
Explanation:
A person riding in an elevator subjected to a series of unbalanced forces depending on the direction the elevator is travelling.
Two forces are acting on the person; the force of gravity and the upward normal force from the elevator.
When the elevator is going upwards with acceleration a, the person feels heavier than his normal weight, due to the upward normal force being greater than the person's weight. N = mg + ma
When the elevator is moving downwards with acceleration a, the person feels lighter due to the downward normal force being less than the person's weight. N = mg - ma
However, when the elevator is moving up or down at constant velocity ie. acceleration a = 0, the person experience a normal force equal to weight. N = mg
When the elevator is moving downwards with acceleration a = g, the person experiences weightlessness. N = (mg - mg) = 0
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