Answer:
Her altitude as she crosses the bar, h₂ is approximately 6.1 m
Explanation:
The given parameters of the motion of the pole vaulter are;
The mass of the pole vaulter, m = 57 kg
The speed with which the pole vaulter is running, u = 11 m/s
The speed of the pole vaulter when she crosses the bar, v = 1.1 m/s
The acceleration due to gravity, g = 9.8 m/s²
From the total mechanical energy, M.E. equation, we have;
M.E. = P.E. + K.E.
Where;
P.E. = The potential energy of the motion = m·g·h
K.E. = The kinetic energy of the motion = 1/2·m·v²
By the principle of conservation of energy, we have;
The change (loss) in kinetic energy, ΔK.E. = The change (gain) in potential energy, ΔP.E.
ΔK.E. = 1/2·m·(v² - u²)
ΔP.E. = m·g·(h₂ - h₁)
Where;
h₁ = The ground level = 0 m
h₂ = The altitude with which she crosses the bar
∴ 1/2·m·(v² - u²) = m·g·(h₂ - h₁)
(h₂ - h₁) = (v² - u²)/(2·g) = (11² - 1.1²)/(2·9.8) = 6.11173469388
h₂ = 6.11173469388 + h₁ = 6.11173469388 + 0 = 6.11173469388
h₂ = 6.11173469388
Her altitude as she crosses over the bar, h₂ ≈ 6.1 m.
A laser beam from Earth is reflected by a mirror placed on the Moon. If the speed of the beam is 3.00 x 108 m / s and the distance from Earth to the Moon is 3.81 x 108 m, how long in seconds will the laser beam take to return to its starting point?
Answer:
1.27seconds
Explanation:
Speed = 324 m/s , Distance = 411.48m
Time = Distance/Speed
Time = 411.48/324 seconds
Time = 1.27seconds ( Ans)
Help! will give brainliest!
Answer:
I would say increasing the balls kinetic energy
Explanation:
Because she is moving the ball and increasing kinetic energy
HELPP!!!
1)Explain how a diode could be used to convert a.c. to d.c., and suggest one disadvantage of this.
2) Some energy is always transferred to the surroundings when a current flows through a wire.
a) How is this energy transferred?
b) Is this energy always wasted energy? Explain your answer.
3) You can induce an electric current in a wire by moving a magnet relative to the coil.
A) Describe two different ways in which you can increase the size of the induced current.
B) Describe how you can reverse the direction of the induced current.
Try to split the questions for easy access
Particulate Motion Unit Test
1. There are two pieces of copper. Piece A is at 70 degrees, while piece B is at 150 degrees. Which piece has more thermal energy? (1 point)
Piece A, because its particles move slower
Piece B, because its particles move faster
Piece A, because its particles move faster
Piece B, because its particles move slower
2. The electrons in the copper atoms in a wire start to move when an electric potential difference is introduced. Which statement about this situation is true?(1 point)
The macroscopic movement of the electrons creates a microscopic flow of electricity.
The macroscopic movement of the electrons creates a macroscopic flow of electricity.
The microscopic movement of the electrons creates a macroscopic flow of electricity.
The microscopic movement of the electrons creates a microscopic flow of electricity.
3. Which statement describes the gravitational energy and energy stored in a magnetic field when objects are drawn close to each other?(1 point)
Both gravitational energy and energy stored in a magnetic field attract.
Both gravitational energy and energy stored in a magnetic field repel.
Gravitational energy attracts; energy stored in a magnetic field attracts or repels.
Gravitational energy attracts; energy stored in a magnetic field repels.
4. A scientist is heating a piece of metal and measuring its temperature. She observes that the temperature of the metal is rapidly increasing. Which statement is correct about the thermal energy of the metal? (1 point)
Thermal energy will increase for as long as temperature is increasing.
Thermal energy will increase for as long as the metal is in solid state.
Thermal energy will increase for as long as the metal is absorbing heat energy.
Thermal energy will increase for as long as the potential energy is zero.
5. A student places a piece of ice inside a glass beaker at room temperature and heats them until they both come to 70°C. Which statement is correct about the energies of the ice and beaker? (1 point)
The thermal energy of the beaker has increased more than the thermal energy of the ice.
The thermal energy of the ice has increased more than the thermal energy of the beaker.
The potential energy of both the ice and beaker have increased the same amount.
The kinetic energy of both the ice and beaker have increased the same amount.
6. Which energy types are both examples of energy on a macroscopic scale?(1 point)
chemical energy and gravitational potential energy
thermal energy and spring potential energy
gravitational potential energy and kinetic energy
kinetic energy and thermal energy
7. A high diver steps off the diving platform and begins falling toward the pool of water below. Which statement about this situation is correct?(1 point)
The amount of energy that is transferred to thermal energy due to friction will be greater at the the top of the fall than at the bottom of the fall.
The gravitational potential energy of the diver decreases as it changes to kinetic energy.
The kinetic energy of the diver decreases as the diver approaches the water.
The gravitational potential energy of the diver increases because of the change in thermal energy due to friction.
8. For a system that contains a rock falling through the air, which situation is always true?(1 point)
The total potential energy of the system is conserved.
The total kinetic energy of the system is conserved.
The total mechanical energy of the system is conserved.
The total energy of the system is conserved.
Answer:
1. piece b because it’s particles move faster.
2. the microscopic movement of the electrons creates a macroscopic flow of electricity.
3. gravitational energy attracts; energy stored in a magnetic field attracts or repels.
4. thermal energy will increase for as long as the metal is absorbing heat energy.
5. the thermal energy of the ice has increased more than the thermal energy of the beaker.
6. gravitational potential energy and kinetic energy
7. the gravitational potential energy of the river decreases as it changes to kinetic energy
8. the total energy of the system is conserved.
Explanation:
just took the test; these are all correct!
For a system that contains a rock falling through the air, the total mechanical energy of the system is conserved.
The piece that has a greater thermal energy is the piece that is at higher temperature because Piece B has particles that move faster. The statement that is true regarding electron movement in a copper wire is that; "the microscopic movement of the electrons creates a macroscopic flow of electricity."The energy stored in a magnetic field is related to the gravitational energy by the statement; "gravitational energy attracts; energy stored in a magnetic field attracts or repels."The statement that is correct about the metal whose temperature is increasing rapidly is; "thermal energy will increase for as long as temperature is increasing."The statement that is true about the ice inside a glass beaker is that; "the kinetic energy of both the ice and beaker have increased the same amount."The energy types that are both examples of energy on a macroscopic scale are chemical energy and gravitational potential energy.As the diver steps off the diving platform and begins falling toward the pool of water below, the gravitational potential energy of the diver decreases as it changes to kinetic energy.For a system that contains a rock falling through the air, the total mechanical energy of the system is conserved.Learn more about mechanical energy: https://brainly.com/question/15025401
If you were to look at grains of table salt with a magnifying glass, you would see that each grain is a little cube. Why are salt grains cubical?
Answer:
All extended structure compounds form cubes. Sodium and chlorine atoms both have cubical shapes. In the extended structure of NaCI, atoms are arranged in a cubical pattern
A large pendulum swings in the lobby of the United Nations building in New York City. The pendulum has a 91-kg gold-plated bob and a length of 22.9 m. Assume g = 9.81 m/s2.
Part A
How much time does it take for the bob to swing from its maximum displacement to its equilibrium position?
Express your answer to three significant figures and include the appropriate units.
Answer:
t = 2.40 s
Explanation:
It just told me
In a binary ionic compound, the electrons are
Answer:
Transferred from one atom to another
Explanation:
In a binary ionic compound, the electrons are transferred from one atom to another, thus forming positive and negative charges on the respective atoms involved, and thereby creating electrostatic forces which thus form the ionic bond.
Answer:transfered from the metal to the nonmetal
Explanation:i took the quiz:)
A student throws a 0.22 kg rock horizontally at 20.0 m/s from 10.0 m above the ground. Find the initial kinetic energy of the rock.
Answer:
44J
Explanation:
Given parameters:
Mass of rock = 0.22kg
Initial velocity = 20m/s
Distance moved = 10m
Unknown:
Initial kinetic energy of the rock = ?
Solution:
To solve this problem, we need to understand that kinetic energy is the energy due to the motion of a body.
It is mathematically expressed as;
Kinetic energy = [tex]\frac{1}{2}[/tex] m v²
m is the mass
v is the velocity
Kinetic energy = [tex]\frac{1}{2}[/tex] x 0.22 x 20² = 44J
A spring with a spring constant of 400 n / M has a mass hung on it so it stretches 8 cm. calculate how much mass the spring is supporting.
Answer:
3.3kg
Explanation:
Given parameters:
Spring constant = 400N/m
Extension = 8cm = 0.08m
Unknown:
Amount of mass the spring is supporting = ?
Solution:
To solve this problem:
F = kE
F is the force
k is the spring constant
E is the extension
So;
F = 400 x 0.08 = 32N
Mass;
Force = mass x acceleration due to gravity
32 = mass x 9.8
Mass = 3.3kg
The mass the spring is supporting is 3.27 Kg.
We'll begin by calculating the force acting on the spring.
Spring constant (K) = 400 N/mExtension (e) = 8cm = 8 / 100 = 0.08 mForce (F) =?F = Ke
F = 400 × 0.08
F = 32 N
Finally, we shall determine the mass. This can be obtained as follow:
Force (F) = 32 NAcceleration due to gravity (g) = 9.8 m/s²Mass (m) =?m = F / g
m = 32 / 9.8
m = 3.27 Kg
Therefore, the mass the spring is supporting is 3.27 Kg
Learn more about spring constant:
https://brainly.com/question/13511965
Please answer the question for gravitational field attached in the image.
We are given:
Radius of Venus= 6 * 10⁶ m
Height above the planet's ground = 9.4 * 10⁶ m
Mass of Venus = 4.867 * 10²⁴ kg
Finding the Gravitational Field:
We first need to calculate the distance between the center of masses
Distance between center of masses:
Since the point is above the surface of Venus, the radius of Venus and the height will add
Distance between the center of masses = 9.4*10⁶ + 6 * 10⁶
Distance (r) = 15.4 * 10⁶ m
Now back to Gravitational field!
We know the formula for Gravitational Field:
g = GM / r² [where g is the gravitational field, M is the mass of the planet, r is the distance between the center of masses and G is the gravitational constant]
plugging the known values in the formula:
g = (6.67 * 10⁻¹¹ * 4.867 * 10²⁴) / (15.4*10⁶)² [G = 6.67*10⁻¹¹ Nm²/kg²]
g = (32.46 * 10¹³) / (237 * 10¹²)
g = (32.46 * 10¹³) / (23.7 * 10¹³)
g = 32.46/23.7 [the 10¹³ got cancelled out]
g = 1.367 N/kg² (or m/s²)
Particulate Motion Unit Test Part 2
1. A gas leak where methane gas combines with oxygen in the air can start a fire, releasing its energy at ignition temperature.
What does the ignition have to do with this chemical reaction?
(1 point)
The ignition provides the energy to break the bonds in molecules and start the reaction.
The ignition adds more atoms to increase its energy during the reaction.
The ignition targets methane gas only and releases oxygen before the fire.
The ignition forces atoms to combine and start a reaction.
2.
Particulate Motion Unit Test
10 of 16Items
Item 10
Gasoline has various chemicals that contain large amounts of chemical potential energy that is released when burned in a car engine.
What happens to the energy produced by burning gasoline in a car engine?
(1 point)
The energy multiplies to keep the engine running.
Some of the energy is lost as heat.
None of the energy is transformed but is sustained as work to run the engine.
The energy released is less than the energy absorbed by the molecules.
3. The reaction between methane gas and oxygen to produce carbon dioxide and water is an exothermic process. Which statement describes the energy in the system?(1 point)
The chemical energy of the reactants is greater than the chemical energy of the products. Energy is absorbed from the surroundings.
The chemical energy of the reactants is greater than the chemical energy of the products. Energy is released to the surroundings.
The chemical energy of the reactants is less than the chemical energy of the products. Energy is released to the surroundings.
The chemical energy of the reactants is less than the chemical energy of the products. Energy is absorbed from the surroundings.
4. How does the energy in the light of the aurora borealis compare to the energy as an excited electron returns to its original energy level?(1 point)
half of the energy
one-third of the energy
equal to
twice the energy
5. A solar flare causes the sun to release a large number of particles along with excess amounts of electromagnetic radiation. Which helps prevent this radiation from harming Earth’s living organisms?(1 point)
Earth’s magnetic field absorbs most of this radiation.
Earth’s magnetic field deflects most of this radiation.
Satellites directly deflect most of this radiation.
Satellites indirectly absorb most of this radiation.
6. Several energy transfers occur during the process of the aurora borealis. During which transfer is the energy the greatest?(1 point)
Energy is the same at each step.
Electrons from the sun transfer energy to atoms in the atmosphere.
Electrons fall and release energy as light.
Electrons in the atoms jump to a higher energy level.
7. Develop a model and use it to explain in 3–4 sentences why a person feels cold when rubbing alcohol is applied to skin. (4 points)
8. Using the concepts of macroscopic and molecular scales of energy, describe in 1–2 sentences how the heating element of a toaster works.(2 points)
Explanation:
The ignition provides the energy to break the bonds in molecules and start the reactionThe energy multiplies to keep the engine runningThe chemical energy of the reactants is greater than the chemical energy of the products. Energy is released to the surroundings.twice the energyEarth’s magnetic field deflects most of this radiation.Electrons in the atoms jump to a higher energy level.it is because alcohol i.look on photo. look it upForce is a push or pull that causes an object to change speed change direction or to change ___ or _____.
Answer:
acceleration or velocity
Explanation: