Answer: When work is positive, the environment does work on an object
Explanation:
The correct option is a)When work is positive, the environment does work on an object.
What is positive and negative work done ?
If work is done on the system , positive work is done on the system because energy enters the system in case of positive work done .If work is done by the system , work done will be negative
According to work energy theorem , change in kinetic energy is equal to work done . when energy enters in the system that means final energy is greater than the initial energy of the system , which implies positive work is done on an object .
this implies , correct option is a)When work is positive, the environment does work on an object.
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what element has 3 protons and 4 electrons?
Answer:
Li⁻
Explanation:
# of protons = # element on the Periodic Table.
# of protons (+) + # of electrons (-) = overall charge
3 protons is the 3rd element on the Periodic Table: Lithium
All elements on the Periodic Table have a neutral charge. Lithium neutral has 3 protons and 3 electrons.
We are given 4 electrons; 3 + -4 = -1 charge overall.
Therefore, our ion is Li⁻
On an icy day, you worry about parking your car in your driveway, which has an incline of 12º. Your neighbor's driveway has an incline of 9.0º, and the driveway across the street is at 6.0º. The coefficient of static friction between tire rubber and ice is 0.15. Which driveway(s) will be safe to park in?
Answer:
Driveway across the street ([tex]\theta = 6^{\circ}[/tex]) is the only choice for a safe parking.
Explanation:
Let suppose that car is represented by a particle, then we proceed to construct its free body diagram and corresponding equations of equilibrium:
[tex]\Sigma F_{x'} = f - W\cdot \sin \theta = 0[/tex] (Eq. 1)
[tex]\Sigma F_{y'} = N-W\cdot \cos \theta = 0[/tex] (Eq. 2)
Where:
[tex]f[/tex] - Static friction force, measured in newtons.
[tex]N[/tex] - Normal force on the car from the ground, measured in newtons.
[tex]W[/tex] - Weight of the car, measured in newtons.
[tex]\theta[/tex] - Driveway inclination, measured in sexagesimal degrees.
By applying definitions of maximum static friction force and weight, we expand the system of equations presented above:
[tex]\mu_{s}\cdot N -m\cdot g\cdot \sin \theta = 0[/tex] (Eq. 1b)
[tex]N - m\cdot g \cdot \cos \theta = 0[/tex] (Eq. 2b)
Where:
[tex]\mu_{s}[/tex] - Static coefficient of friction, dimensionless.
[tex]m[/tex] - Mass of the car, measured in kilograms.
[tex]g[/tex] - Gravitational acceleration, measured in meters per square second.
Then, we substitute normal force and simplify the resulting expression:
[tex]\mu_{s}\cdot m\cdot g \cdot \cos \theta -m\cdot g \cdot \sin \theta = 0[/tex]
[tex]\mu_{s} = \tan \theta[/tex]
[tex]\theta = \tan^{-1}\mu_{s}[/tex] (Eq. 3)
Based on such result, we can conclude that if driveway inclination is greater than value reported, then car shall not be safe in case of parking. Our reference angle is: ([tex]\mu_{s} = 0.15[/tex])
[tex]\theta = \tan^{-1} 0.15[/tex]
[tex]\theta \approx 8.531^{\circ}[/tex]
By direct comparison, we find that driveway across the street ([tex]\theta = 6^{\circ}[/tex]) is the only choice for a safe parking.
1. Who were the first three countries to build rocket engines?
O Russia, Germany, China
O Germany, China, Canada
O Russia, USA, Germany
O USA. China, Russia
Answer:
i think its Russia, USA, Germany.
what is the unit of magnetic field
Answer:
Hope this helps!~ (Sorry if you get it wrong or I got it wrong-)
Explanation:
The standard SI unit for magnetic field is the Tesla, which can be seen from the magnetic part of the Lorentz force law Fmagnetic = qvB to be composed of (Newton x second)/(Coulomb x meter). A smaller magnetic field unit is the Gauss (1 Tesla = 10,000 Gauss).
~The Confuzzeled homan
Why is the unit of momentum called derived unit
Answer:
the SI unit of momentum is :- kg.ms-1
and we know that,
kinetic energy = 1/2 mv2
E=p2/2m
p=(2Em)1/2
so the derived units are (J.kg)1/2
Explanation:
The question is 6 please help
Answer:
none of the answers are correct
Explanation:
Lithium = 3
Berillium = 4
Boron = 5
Carbon = 6
Which statement best describes what Kendall can do?
Answer: Explanation:
She can measure the volume and mass of the marble, the volume and mass of the water, and the volume and mass of the graduated cylinder. She can measure the volume and mass of the marble, the volume and mass of the water, and the mass of the graduated cylinder.
A spacejet travels 800 miles/h .how long does it take to travel 1km
An 85 kg construction worker has 37,485J of gravitational potential energy. To the nearest whole number,
worker is _________
mabove the ground
Answer:
45m above the ground
Explanation:
got it right on Edg 2020
How much work is done to move a 1,000 N car 20 meters?
Answer:
The answer is 20,000 JExplanation:
The work done by an object can be found by using the formula
workdone = force × distanceFrom the question
force = 1,000 N
distance = 20 m
We have
workdone = 1000 × 20
We have the final answer as
20,000 JHope this helps you
1) Calculate the speed of a runner who runs 100 m in 20s
This is how you calculate his speed, for the 100metres. That is, the average speed for the entire distance, including the start from intertia until the race end where the athlete is decelerating. Multiply the time by 10, and divide 3600 by that figure. i.e. 10 by10 equals 100. Divide 3600 by 100 and you get 36 which is the speed figure you requested.
A female athlete ran 200 metres a few years ago and in the middle section of the race covered 100 metres in that race in a time under 10 seconds. That is, she ran a sub 10second 100metres from a flying start. This great athlete from Slovenia, also ran a 100 metre race (from a stationary start) in a time under 11 seconds, when she was 48 years of age. Her name is Merlene Ottey.
Which answer choice
describes all nonmetals?
A. Hydrogen and all of the elements in blue boxes
B. All of the elements of Period 2 in green boxes
O C. All of the elements of Group 18 in orange boxes
D. Hydrogen and all of the other elements in orange boxes
Hydrogen and all of the other elements in orange boxes are non metals and is denoted as option D.
What is a Non metal?These are elements which lack metallic properties and usually have low thermal and electrical conductivity.
In the periodic table, they are represented by orange together with hydrogen hence the reason why it is the most appropriate choice.
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You are riding a bicycle. If you apply a forward force of 172 N, and you and the bicycle have a combined mass of 51 kg, what will be the forward acceleration of the bicycle? (Assume there is no friction)
Answer:
The answer is 3.37 m/s²Explanation:
The acceleration of an object given it's mass and the force acting on it can be found by using the formula
[tex]acceleration = \frac{force}{mass} \\[/tex]
From the question
force = 172 N
mass = 51 kg
We have
[tex]acceleration = \frac{172}{51} \\ = 3.372549019...[/tex]
We have the final answer as
3.37 m/s²Hope this helps you
What should be the ending of the second element in a covalent compound?
-ide
-ium
the prefix
the subscript
Answer:
-ide
Explanation:
the second element is names by taking the stem of the element name and adding -ide. a system if numerical prefixes is used to specify the the number if atoms in a molecule.
Answer:
A. -ide
Explanation:
PHYSICAL SCIENCE, PLEASE HELP!
Which items are matter?
Answer:
Mobile phone & battery.
What is the magnitude of force required to accelerate a car of mass
1.7 × 103 kilograms by 4.75 meters/second2?
Answer:
The answer is 8075 NExplanation:
The force acting on an object given it's mass and acceleration can be found by using the formula
force = mass × accelerationFrom the question
mass = 1.7 × 10³ kg = 1700 kg
acceleration = 4.75 m/s²
We have
force = 1700 × 4.75
We have the final answer as
8075 NHope this helps you
What is a non-example of Newton's 3rd law of motion?
Answer:
Unbalanced forces are not examples of Newton's third law because not all opposite reactions are unbalanced forces.
Explanation:
The two factors that determine velocity are
A: speed and direction
B: direction and speed
C: position and rate
D:distance and mass
PLEASE HELP ME
Answer:
A: speed and direction
For a substance to change from a gas to a liquid, what must happen to its particles?
A ping pong ball rolls off a 5.Om high table and lands on the floor, 3.0m
away from the table. How long is the ball in the air?
Answer:
The ball was 1.01 seconds in the air
Explanation:
Horizontal Motion
When an object is thrown horizontally with a speed v from a height h, the range or maximum horizontal distance traveled by the object can be calculated as follows:
[tex]\displaystyle d=v\cdot\sqrt{\frac {2h}{g}}[/tex]
If we know the value of d and h, we can solve the equation for v:
[tex]\displaystyle v=d\cdot\sqrt{\frac {g}{2h}}[/tex]
Since the horizontal speed is constant, we can calculate the time the ball was in the air by using the equation:
[tex]\displaystyle t=\frac{d}{v}[/tex]
The ping pong ball rolls from a height of h=5 m and lands on the floor a distance of d= 3 m away from the table. Calculate the speed:
[tex]\displaystyle v=3\cdot\sqrt{\frac {9.8}{2\cdot 5}}[/tex]
[tex]\displaystyle v=3\cdot\sqrt{\frac {9.8}{10}}[/tex]
Calculating:
[tex]v=2.97\ m/s[/tex]
Now calculate the time:
[tex]\displaystyle t=\frac{3}{2.97}[/tex]
[tex]t=1.01\ sec[/tex]
The ball was 1.01 seconds in the air
Note: The time does not depend on the distance d at all. If we borrow the equation from free-fall motion, the time can be calculated with:
[tex]\displaystyle t=\sqrt{\frac {2h}{g}}=\sqrt{\frac {10}{9.8}}=1.01\ sec[/tex]
when a light bulb is turned on electrical energy is transformed into two other types of energy. What are they and support your answer
Answer:
In the case of an electric bulb, the electrical energy is converted to light and heat. The amount of electrical energy put into a bulb = the amount of light energy (desirable form) plus the heat energy that comes out of the bulb (undesirable form).
Explanation:
sana nakatulong)):
What is the legal height the player is allowed to serve from a. Above the waist B. Below the waist C. On the waist D. above the chest
Answer: Option B.
Explanation:
I guess that this refers to the Badminton rules, particularly to the position of the racket (or the head of the racket, where the "head" is the part with the net, that you use to hit the shuttle) when serving.
The head of the racket must be swung from below your waist. So the head of the racket must be below your waist before you do the service (With a part of the head is enough).
Then the correct option is B. Below the waist.
When energy is transferred from one part of a system to another, some of the
energy is lost during the transfer and cannot be used as it was intended.
Which two sentences describe examples of this?
A. An electric motor hums as it powers a conveyor belt
B. Stereo speakers emit sound when powered by electrical energy.
O C. Sunlight strikes a solar panel, generating electricity.
O D. A car engine heats up while the car is being driven.
E. Wind moves a turbine, generating electricity.
Answer:
A. An electric motor hums as it powers a conveyor belt
D. A car engine heats up while the car is being driven.
Explanation:
Energy inefficiency usually involves loss of energy as other forms when they are being converted from one form to another.
The two choices that fit the description includes;
An electric motor humming as it powers a conveyor belt. This energy conversion is supposed to be from electrical to mechanical energy but there is a loss due to the sound energy produced by the motor. Heat energy produced as the car is driven also results in energy inefficiency.Other choices do not show this inefficiency.
Answer:
A. An electric motor hums as it powers a conveyor belt
D. A car engine heats up while the car is being driven.
Explanation:
Which types of data should be modified to change the rate of rotation?
(1 point)
o the number of loops in the coil and the distance from the source of the current
o the number of loops in the coil and the electric current
the dimensions of coils and the distance from the source of the current
o the dimensions of the coils and the electric current
Answer:
the number of loops in the coil and the electric current.
Explanation:
Just took the test and got it correct.
Rashid lifts a flower pot 0.8m off the floor using a constant force of 20 N. How much work is done on the flower pot?
Answer:16 J
Explanation:
Work done = force × displacement
In this case the body has been displaced to a height
Melanie and Lance gathered data about the effectiveness of masks
preventing disease. One of the questions they ask the experimental
subjects is their age. What type of observation is this? *
Explain how mass and velocity play a big role in the amount of momentum an object has.
Answer:
Momentum is directly proportional to the object's mass and also its velocity. Thus the greater an object's mass or the greater its velocity, the greater its momentum. Momentum p is a vector having the same direction as the velocity v. The SI unit for momentum is kg · m/s.
Answer:
Momentum is directly proportional to the object's mass and also its velocity. Thus the greater an object's mass or the greater its velocity, the greater its momentum. Momentum p is a vector having the same direction as the velocity v. The SI unit for momentum is kg · m/s.
Explanation:
WILL REWARD brief history of nuclear power. inventors and or who discovered nuclear power and when it was first used.
Answer:
1951 an experimental nuclear reactor in Arco, Idaho, produces enough electricity to power for light bulbs...... 1954 the atomic energy act authorizes development of nuclear energy for a civilian use.1957 first commercial nuclear-powered Generating Station is built in the shippingport,Pa.Explanation:
● Enrico Fermi was the one who discovered nuclear power.
● nuclear power was first used
[ December 20, 1951]
how long does it take a dollar bill that is 6 inches long to drop through its length (hint: Convert the length to meters and use a formula to find the time taken for the dollar to free fall through this length)
Answer:
3.4seconds
Explanation:
if a dollar was times for how long it would fall down to its length it would be 3.4 seconds
127) A swimmer heading directly across a river that is 200 m wide reaches the opposite bank in
6 min 40 s. During this swim, she is swept downstream 480 m. What is the speed of the
current?
A) 0.50 m/s
B) 0.80 m/s
C) 1.2 m/s
D) 1.4 m/s
E) 1.8 m/s
Answer:
C
Explanation: