When a car spends two hours driving at 20 km/h, and then an hour driving at 50 km/h. then the average speed of the car would be 30 km/h , therefore the correct answer is option D.
What is speed?The total distance covered by any object per unit of time is known as speed. It depends only on the magnitude of the moving object. The unit of speed is meter/second. The generally considered unit for speed is a meter per second.
The mathematical expression for speed is given by
average speed = total distance /Total time
As given in the problem A car spends two hours driving at 20 km/h, and then an hour driving at 50 km/h
The total distance covered by the car is
S =2×20 +1×50
=90 km
The total time taken by the car is
T = 3 hour
then by using the formula for the average speed
average speed = total distance /Total time
By substituting the respective values of the total speed and total time
average speed = 90/3 km/h
=30 km/h
Thus, The correct answer is option D because a car's average speed would be 30 km/h if it spent two hours traveling at 20 km/h and one hour traveling at 50 km/h.
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These data tables show the distance of various galaxies from Earth in millions of light-years (Mly) at different times. Which table supports the theory of expansion in the formation of the universe?
Answer: it’s b
Explanation:
I had two attempts to do the test first I picked c but I did it again it’s b .
drawing of a ray diagram showing how image is formed between principal focus and centre of curvature.
Answer:
When the object is placed between centre of curvature and principal focus of a concave mirror the image formed is beyond C as shown in the figure and it is real, inverted and magnified.
solution
Petter performed an experiment to test which of the three compounds his teacher game him was an ionic compound. Which compound (A, B, or C) is most likely an ionic compound?
Which correctly describes how the energy of a wave on the electromagnetic
spectrum depends on wavelength and frequency?
O A. Energy decreases with decreasing wavelength and decreasing
frequency
B. Energy increases with decreasing wavelength and decreasing
frequency
O C. Energy increases with decreasing wavelength and increasing
frequency
D. Energy decreases with increasing wavelength and increasing
frequency
Answer:
C. Energy increases with decreasing wavelength and increasing frequency
Explanation:
A .5kg ball is tied to a 1 meter long string and swung in a vertical circle at a velocity of 4 m/s. Find the tension in the string at:
A-Top of the Circle
B-Bottom of the Circle
Answer:
A-Top of the Circle
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A 68-kg skydiver has a speed of 52 m/s at an altitude of 670 m above the
ground. Determine the kinetic energy possessed by the skydiver, KE =
1/2mv^2*
Answer:
91936J
Explanation:
We know that kinetic energy= 1/2 mv^2
M= mass = 68 Kg
v= velocity= 52 m/s
KE=1/2 × 68 × (52)^2
KE= 1/2 × 68 × 2704
KE= 91936J
What is the momentum of a 31.2 kg object traveling at a velocity of 2.1 m/s?
Answer:
p = 65.52 kg m/s
Explanation:
p = m × v
p = 31.2 × 2.1
p = 65.52 kg m/s
The capacitance of each capacitor is 1μF. Find the total capacitance
If a device uses mains electricity at 230v and has a 13a fuse in the plug wht is the maximmum power it can safley use?
Answer:
2990W
Explanation:
Given parameters:
Voltage = 230V
Current = 13A
Unknown:
Maximum power it can safely use = ?
Solution:
To solve this problem;
Power = Current x Voltage
Power = 230 x 13 = 2990W
What is the main idea of this text of "Phillis Wheatley"
Answer:
The main idea of the text is to tell you how Phillis wheatley grew up and what the person life was like
Timed! I would really appreciate some help! thank you!
Andy runs for 30 minutes at a speed of 10km/h. How far did he run? (Hint: remember to convert the minutes to hours before calculating distance.) *
3km
5km
150km
Answer:
x = 5[km]
Explanation:
We must convert the time from minutes to hours.
[tex]t=30[min]*\frac{1h}{60min}= 0.5[h]\\[/tex]
We know that speed is defined as the relationship between space and time.
[tex]v=x/t[/tex]
where:
x = space [m]
t = time = 0.5 [h]
v = velocity [m/s]
Now replacing:
[tex]x = 10[\frac{km}{h} ]*0.5[h]\\x=5[km][/tex]
Which example provides a complete scientific description of an object in motion?
the gravitational potential energy of an object is due to
a .its mass
b .its acceleration due to gravity
c. its height above the earth' s surface
d .all of these
d. all of these
look at the picture to know from where we get this law with application on it
A sound wave traveling through dry air has a frequency of 16 Hz, a wavelength of 22 m, and a speed of 350 m/s. When the sound wave passes through a cloud of nitrous oxide, its wavelength changes to 16 m, while its frequency remains the same. What is its new speed? (The equation for the speed of a wave is v= f x 1.)
A. 350 m/s
B. 16 m/s
C. 5,600 m/s
D. 256 m/s
It's D
Answer:
D. 256 m/s
Explanation:
[tex]f[/tex] = Frequency of the wave = [tex]16\ \text{Hz}[/tex]
[tex]\lambda[/tex] = Wavelength = [tex]16\ \text{m}[/tex]
Speed of a wave is given by
[tex]v=f\lambda[/tex]
[tex]\Rightarrow v=16\times 16[/tex]
[tex]\Rightarrow v=256\ \text{m/s}[/tex]
The speed of the wave as it passes through the cloud of nitrous oxide is [tex]256\ \text{m/s}[/tex].
Answer:
D. 256 m/s
Explanation:
d. d as in dog
Ifa truck starts from rest and it has acceleration of 4 m/s for 5 second
calculate its final velocity. What will be the distance travelled by the track
during the time interval?
Answer:
Distance 50m
final velocity 20ms^-1
[tex]s = ut + \frac{1}{2} a {t}^{2} \\ = 0 \times t + \frac{1}{2} \times 4 \times {5}^{2} = 50m[/tex]
[tex]v = u + at \\ v = 0 + 4 \times 5 \\ v = 20ms^{ - 1} [/tex]
A 64 kg swimmer jumps, with a velocity of 4.2 m/s, off the front of a 25 kg kayak when the kayak is moving forward at a velocity of 3.2 m/s. What is the velocity of the kayak after the swimmer jumps off
Answer:
3.88m/s
Explanation:
Using the law of conservation of momentum
m1u1+m2u2 = (m1+m2)v
m1 and m2 are the masses
u1 and 2 are the initial velocities
v is the final velocity
Given
m1 = 64kg
u1 = 4.2m/s
m2 = 25kg
u2 = 3.2m/s
Required
Final velocity v
Substitute the given values into the formula
64(4.2)+25(3.2) = (65+25)v
268.8+80 = 90v
348.8 = 90v
v = 348.8/90
v = 3.88m/s
Hence the velocity of the kayak after the swimmer jumps off is 3.88m/s
A car is stopped at a stop light. When the light turns green, it travels south 55 m/s in 5s. What is its acceleration? *
Answer:
11m/s^2
Explanation:
Acceleration can be calculated by diving speed by time. Since we know speed and time, acceleration can be calculated.
55/5 = 11m/s^2
A major league pitcher can throw a baseball with a kinetic energy of 150 J. How much work must the pitcher do to the ball to give it that much KE?
A.) 150 J
B.) 0 J
C.) can't tell without knowing the mass of the ball
D.) 75 J
Answer:
A= 150 J
Explanation:
Kinetic energy is the energy of an object in motion.
The formula for kinetic energy is ;
K.E = 1/2 * m *v² where m is mass and v is velocity
Work done is equal to change in kinetic energy
W= Δ K.E
Given that K.E = 150 J
Taking that the ball was stationary before it was thrown, this makes its initial kinetic energy to be 0 J so the work done will be
W= Δ K.E
W= 150 - 0
W= 150 J
Mechanical engineers generally work in all of the following EXCEPT
•marine biology.
•aerospace products.
•automotive industry.
•computers and electronics.
Answer:
•marine biology.
Explanation:
A mechanical engineer is a professional individual who ensures the design of a mechanical assembly as well as the monitoring of its realization. His role involves the manufacturing of a prototype and developing new products for the company. Responsible for manufacturing, he advises the company and customers and assesses the risks and techniques used for its development. Finally, he supervises the installation and the market penetration of the product, as well as its maintenance.
A mechanical engineer can collaborate with many useful and complementary professions such as designers or marketers, it ensures the appearance and technical operation of the product. It is a job under high responsibility with projects that can be large.
Finally, he can also work in the construction sector, in the automotive industry, biomechanics, shipbuilding, aerospace production and aeronautics, railways, mechanics and metallurgy, robotics, textile machinery, etc.
Explain the answer for the below Question
What group of the periodic table is this atom in?
Answer:
Group 3
Explanation:
In groups moving from top to bottom in a group, valency remains same because number of valence electron remains same.
eg . valency of first group elements = 1
valency of second group = 2
valency of third group = 3
Hope it is useful
NEED IT ASAP!!!!!!!!!!!!!!!!!!!!!
Many people experiment with a gateway drug.
A. before they try other drugs.
B. after they've tried other drugs.
C. only once.
Answer:B
Explanation:onec thwy tried others
please help answer worth 15!!
Answer:
Correct answers are B and C.
Explanation:
The line segment which exhibits a positive uniform accelaration if and only if [tex]\Delta v > 0[/tex] for [tex]\Delta t > 0[/tex]. According to this statement, the line segments B and C exhibits positive uniform accelerations, whereas line segments A and D have a constant velocity and line segments E exhibits a negative uniform acceleration.
Hence, correct answers are B and C.
Pleaseeeee help me with b, c, and d. There are no angles.
Answer:
a. 150 J
b. 150 J
c. 0 J
d. 0 J
Explanation:
The given parameters are;
The horizontal force with which the man pulls the canister, F = 50 N
The distance he moves the vacuum cleaner, d = 3.0 m
a. Work done, W = Force applied, F × Distance moved by the force, d
Therefore, for the work done by the 50 N force on the canister, we have;
W = 50 N × 3.0 m = 150 N·m = 150 J
b. Given that he pulls the canister at a constant speed, we have;
The acceleration of the canister, a = 0 m/s²
Therefore, the net force on the canister, [tex]F_{NET}[/tex] = F - [tex]F_{Friction}[/tex] = m × a
Where;
m = The mass of the canister
a = The acceleration of the canister
F = The applied force = 50 N
[tex]F_{Friction}[/tex] = The force of friction
∴ [tex]F_{NET}[/tex] = m × a = m × 0 m/s² = 0 N
Therefore;
[tex]F_{NET}[/tex] = F - [tex]F_{Friction}[/tex] = 0 N
From which we have;
F = [tex]F_{Friction}[/tex] = 50 N (The applied force, F is equal to the force of friction,
The work done by friction = The force of friction × The distance in which the force of friction acts
∴ The work done by friction = [tex]F_{Friction}[/tex] × d - 50 N × 3.0 m = 150 J
The work done by friction = 150 J
c. The normal force, N acts perpendicular to the force of friction
The distance the canister moves in the perpendicular direction, [tex]d_p[/tex] = 0 m
∴ The work done by the normal direction = N × [tex]d_p[/tex] = N × 0 m = 0 J
The work done by the normal direction = 0 J
d. The vacuum weight, W, acts on the same line as the normal force but in the opposite direction to the normal force, N
Therefore, the weight, W, acts perpendicular to the line of motion of canister
The distance the canister moves in the direction of the weight, [tex]d_{wieght}[/tex] = 0 m
Therefore, the work done by the weight = W × [tex]d_{wieght}[/tex] = W × 0 m = 0 J
The work done by the weight = 0 J
Respostas
2 M
3 M
5 M
7 M
8 M
ccording to Newton's Second Law, what effect will doubling the mass of an object have?
the weight of an object on the earths surface is 300N. when it is lifted to 3 times the height, its weight will become
Answer:
The weight of the object when it is lifted to 3 times the height is 33.[tex]\overline 3[/tex] N
Explanation:
The given parameters are;
The weight of the object on Earth, W = 300 N
The initial position of the object = On the surface of the Earth
Therefore;
The distance with which the weight is measured = The radius of the Earth, R
By Newton's Law of Gravitation, we have;
[tex]W = G \times \dfrac{M \times m}{R^2}[/tex]
Where;
W = 200 N
G = The universal gravitational constant
M = The mass of the Earth
m = The mass of the object
When the height of the object = 3 × R, the weight of the object, W₂, is given as follows;
[tex]W_2 = G \times \dfrac{M \times m}{(3 \times R)^2} = \dfrac{1}{9} \times G \times \dfrac{M \times m}{ R^2} = \dfrac{1}{9} \times W = \dfrac{1}{9} \times 300 N = 33.\overline 3 \ N[/tex]
Therefore, the weight of the object at 3 times the height, W₂ = 33.[tex]\overline 3[/tex] N
Which factor should change when comparing the boiling times of the liquids?
A. The surface area of the boiling vessel
B. The type of liquid inside the boiling vessel
C. The original temperature of the boiling vessel
D. The volume of liquid inside the boiling vessel
Answer:
B
Explanation:
cause it be like that
B. The type of liquid inside the boiling vessel.
Which liquid is used in boiling point?
Paraffin oil is used for boiling factor willpower as it has a very excessive boiling factor and so it could be used to hold a high temperature within the boiling factor and melting factor equipment without lack of the substance.
Boiling is the process by which a liquid will become a vapor whilst it's miles heated to its boiling point. The alternative from a liquid segment to a gaseous segment occurs while the vapor pressure of the liquid is identical to the atmospheric stress exerted on the liquid.
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When a car is going at a constant velocity down the freeway, is the net force zero or not zero assuming no friction?
Answer:
Zero
Explanation:
The net force acting on an object moving with constant velocity is zero. This is an accordance with the Newton's first law of motion.
Newton's first law of motion states that a body will continue in its state of rest or constant motion unless it is acted upon by an external force.
Since this body is moving with uniform motion, it is not accelerating. When a body is acceleration, the net force on it is not zero.
But this one is moving with uniform motion. The net force on the body is balanced and zero.
