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
A 58-kg boy swings a baseball bat, which causes a 0.140-kg baseball to move toward 3rd base with a velocity of 38.0 m/s.
Calculate the kinetic energy of the baseball (rounding your answer to the integer).
Answer:
101 J
Explanation:
Answer:
[tex]\boxed {\boxed {\sf 101 \ Joules}}[/tex]
Explanation:
Kinetic energy can be found using the following formula:
[tex]KE=\frac{1}{2}mv^2[/tex]
The mass of the baseball is 0.140 kilograms and the velocity is 38.0 meters per second.
[tex]m= 0.140 \ kg \\v= 38.0 \ m/s[/tex]
Substitute the values into the formula.
[tex]KE=\frac{1}{2} [0.140 \ kg][(38.0 \ m/s)^2][/tex]
First, evaluate the exponent.
(38.0 m/s)²= 38.0 m/s * 38.0 m/s = 1444 m²/s²[tex]KE=\frac{1}{2}(0.140 \ kg)(1444 \ m^2/s^2)[/tex]
Multiply the two numbers in parentheses together.
[tex]KE=\frac{1}{2}(202.16 \ kg*m^2/s^2)[/tex]
Multiply the fraction by the number, or divide the number by 2.
[tex]KE=101.08 \ kg*m^2/s^2[/tex]
Round to the nearest whole number. The 0 in the tenth place tells us we can leave the number as is.
[tex]KE\approx 101 \ kg*m^2/s^2[/tex]
1 kg*m²/s² is equal to 1 Joule. Therefore, our answer of 101 kg*m²/s² is equal to 101 Joules (J).
[tex]KE\approx 101 \ J[/tex]
The kinetic energy of the baseball is about 101 Joules.
A truck initially traveling at a speed of 22 m/s increases at a constant rate of 2.4 m/s^2 for 3.2s. What is the total distance travelled by the truck during this?
Answer:
82.7 m
Explanation:
u= 22m/s
a= 2.4 m/s^2.
t= 3.2 secs
Therefore the distance travelled can be calculated as follows
S= ut + 1/2at^2
= 22 × 3.2 + 1/2 × 2.4 × 3.2^2
= 70.4 + 1/2×24.58
= 70.4 + 12.29
= 82.7 m
Hence the distance travelled by the truck is 82.7 m
A man carries a load of mass 2.6kg from one end of a uniform pole 100cm long which has a mass 0.4kg. The pole rest on his shoulder at a point 60.0cm from the load and he holds it by the other end. What vertical force must be applied by his hand and what is the force on his shoulder?
Answer:
F = 39.2 N (hand force) and N = 68.6 N (shoulder force)
Explanation:
In this exercise we must use the rotational and translational equilibrium conditions, we have several forces: the weight (W) of the pole applied at its geometric center, the load (w1) at one end, the shoulder support (N) 60 cm from the load and hand force (F) at the other end of the pole
Let's set the reference system at the fit point of the shoulder
∑ τ = 0
We will assume that the counterclockwise turns are positive
w₁ 0.60 + W 0.1 + F₁ 0 - F 0.4 = 0
all distances are measured from the support of the man (x₀ = 0.60 m)
F = (w₁ 0.60 + W 0.1) / 0.4
F = (m₁ 0.6 + m 0.1) g / 0.4
let's calculate
F = (2.6 0.6 + 0.4 0.1) 9.8 / 0.4
F = 39.2 N
this is the force that the hand must exert to keep the system in balance
We apply the translational equilibrium condition
-w₁ -W + N - F = 0
N = w₁ + W + F
N = (m₁ + m) g + F
let's calculate
N = (2.6 + 0.4) 9.8 + 39.2
N = 68.6 N
HELP NEEDED ASAP I'M GIVING BRAINLIEST
1) Select the best answer from the choices below. Light has many properties of waves, but sometimes it also behaves like:
a
A photon
b
Polarized light
c
Ultraviolet rays
d
A stream of particles
2) What type of waves transmit signals in satellite communication?
a
Microwaves
b
X-rays
c
Gamma Rays
d
Radio Waves
3) Cell phones use digital signals to send and receive information. These digital signals travel as what kind of wave?
a
Gamma rays
b
X-rays
c
Microwaves
d
Radio waves
Answer:
1.
d . A stream of particles
2. D. Radiowave
3. Microwaves
Answer:
1.
d . A stream of particles
2. D. Radiowave
3. Microwaves
Explanation:
PLS HELP THIS IS DUE IN TWO HOURS
Answer:
C
Explanation:
If the velocity of an object is zero, then that object cannot be accelerating. | True or False
Answer: False
Explanation:
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
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.
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
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
Which two fundamental forces are only attractive?
O A. Gravitational and strong nuclear
O B. Electromagnetic and weak nuclear
O C. Electromagnetic and strong nuclear
O D. Gravitational and weak nuclear
The two fundamental forces that are only attractive is A. Gravitational and strong nuclear.
What connection exists between the strong nuclear force and gravity?The "strong" nuclear force outperforms gravity by a factor of 10 to the 38th. While gravitational and electromagnetic forces have relatively large ranges of action, the strong and weak nuclear forces operate at close ranges. All objects are affected by the strong and weak nuclear forces, whereas smaller objects are affected by gravitational and electromagnetic forces.
Nuclear forces are the most enticing of the four fundamental forces. There was no explanation provided as to how the nucleus in the atom is kept together by electromagnetism, which maintains matter together.
Therefore, option A is correct.
Learn more about forces at:
https://brainly.com/question/12970081
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Which has the most momentum?
Select one:
A. 100 kg at rest
B. 20 kg at 2 m/s
C. 5 kg at 50 m/s
D. 10 kg at 5 m/s
Answer: C
Explanation:
A: 100kg*0m/s (obviously not answer)
B: 20kg*2m/s (=40)
C: 5kg*50m/s (=250, safe bet this one is it)
D: 10kg*5m/s (=50)
5 kg at 50 m/s, with a momentum of 250 kg m/s has the most momentum.
Hence, the correct option is C.
To calculate momentum, we use the formula:
Momentum (p) = Mass (m) × Velocity (v)
Let's calculate the momentum for each option:
A. 100 kg at rest
Momentum = 100 kg × 0 m/s = 0 kg m/s
B. 20 kg at 2 m/s
Momentum = 20 kg × 2 m/s = 40 kg m/s
C. 5 kg at 50 m/s
Momentum = 5 kg × 50 m/s = 250 kg m/s
D. 10 kg at 5 m/s
Momentum = 10 kg × 5 m/s = 50 kg m/s
Therefore, 5 kg at 50 m/s, with a momentum of 250 kg m/s has the most momentum.
Hence, the correct option is C.
To know more about momentum here
https://brainly.com/question/30677308
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