Physics : asked on deja212677

04.08.2020

Which situation describes a negative acceleration? A runner slowing
Newton’s second law

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04.06.2023, solved by verified expert

Nitin Arora

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Mathematics, English, Physics. Research Scholar at Indian Institute of Technology, Roorkee

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Answer:

The situation that describes a negative acceleration is: a runner slowing down at the end of a race.

Step-by-step explanation:

In physics, acceleration is the rate at which an object's velocity changes over time. It can be positive, negative, or zero, depending on the direction and magnitude of the velocity change.

When a runner slows down at the end of a race, it means that the runner's velocity is decreasing. Since acceleration is the change in velocity divided by time, a decrease in velocity results in a negative acceleration. This negative acceleration indicates that the runner's speed is decreasing over time, showing a deceleration or slowing down.

The situation that describes a negative acceleration is: a runner slowing down at the end of a race.

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Physics

Bees can see into the ultraviolet region of the electromagnetic spectrum. Compared with humans, bees can sense electromagnetic waves that have a lower frequency and a shorter wavelength. a higher frequency and a longer wavelength. a lower frequency and a longer wavelength. a higher frequency and a shorter wavelength.

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P Answered by Specialist

Options:
a. a lower frequency and a shorter wavelength.
b. a higher frequency and a longer wavelength.
c. a lower frequency and a longer wavelength.
d. a higher frequency and a shorter wavelength

Answer:
d. a higher frequency and a shorter wavelength

Explanation:
The frequency of a wave is inversely proportional to its wavelength. That means that waves with a high frequency have a short wavelength, while waves with a low frequency have a longer wavelength. Light waves have very, very short wavelengths.
For example, Gamma rays have the highest energies, the shortest wavelengths, and the highest frequencies. Radio waves, on the other hand, have the lowest energies, longest wavelengths, and lowest frequencies of any type of EM radiation.
Options:
a. a lower frequency and a shorter wavelength.
b. a higher frequency and a longer wavelen

Physics

An amateur player is about to throw a dart with an initial velocity of 15 meters/second onto a dartboard that is at a distance of 2.7 meters. Calculate the vertical distance by which the player will miss the target if he throws the dart horizontally, in line with the dartboard.

Step-by-step answer

P Answered by Specialist

Options:
a. 0.08 meters
b. 0.16 meters
c. 0.32 meters
d. 1.8 meters

Answer:
b. 0.16 meters

Explanation:
In the picture
Options:
a. 0.08 meters
b. 0.16 meters
c. 0.32 meters
d. 1.8 meters

Answer:
b. 0.16 meters

Physics

Abbey always gets zits on her chin and she can t figure out the best method to get rid of them. She decides to test several products to see which clears her face up fastest: washing with soap and water, washing with an acne face wash from the pharmacy, and washing her face with organic oils. For one week she just washes her face with water. The next week she washes every day with soap and water. The following week she uses the acne wash, and the last week she uses the organic oils. Each week she records the number of zits she has on her chin at

Step-by-step answer

P Answered by PhD

Independent variable: the best method to get rid of them.

Dependent variable: washing with soap and water.

Hypothesis: Organic oils

Control group: water

Physics

A proton (1.6726 ? 10-27 kg) and a neutron (1.6749 ? 10-27 kg) at rest combine to form a deuteron, the nucleus of deuterium or “heavy hydrogen.” In this process, a gamma ray (high-energy photon) is emitted, and its energy is measured to be 2.2 MeV (2.2 ? 10 6 eV).

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P Answered by Master

Answer:

see below.

Step-by-step explanation:

To solve this problem, we can use the conservation of energy and conservation of momentum principles.

Conservation of energy:

The total initial energy is the rest energy of the proton and neutron, which is given by:

Ei = (mp + mn)c^2

where mp and mn are the masses of the proton and neutron, respectively, and c is the speed of light.

The total final energy is the rest energy of the deuteron plus the energy of the gamma ray, which is given by:

Ef = (md)c^2 + Eg

where md is the mass of the deuteron and Eg is the energy of the gamma ray.

According to the conservation of energy principle, the initial energy and final energy must be equal, so we have:

Ei = Ef

(mp + mn)c^2 = (md)c^2 + Eg

Conservation of momentum:

The total initial momentum is zero because the proton and neutron are at rest. The total final momentum is the momentum of the deuteron and the momentum of the gamma ray. Since the gamma ray is massless, its momentum is given by:

pg = Eg/c

where pg is the momentum of the gamma ray.

According to the conservation of momentum principle, the total final momentum must be equal to zero, so we have:

0 = pd + pg

where pd is the momentum of the deuteron.

Solving for md and pd:

From the conservation of energy equation, we can solve for md:

md = (mp + mn - Eg/c^2)/c^2

Substituting this expression into the conservation of momentum equation, we get:

pd = -pg = -Eg/c

Substituting the given values, we have:

mp = 1.6726 × 10^-27 kg mn = 1.6749 × 10^-27 kg Eg = 2.2 × 10^6 eV = 3.52 × 10^-13 J

Using c = 2.998 × 10^8 m/s, we get:

md = (1.6726 × 10^-27 kg + 1.6749 × 10^-27 kg - 3.52 × 10^-13 J/(2.998 × 10^8 m/s)^2)/(2.998 × 10^8 m/s)^2 = 3.3435 × 10^-27 kg

pd = -Eg/c = -(3.52 × 10^-13 J)/(2.998 × 10^8 m/s) = -1.1723 × 10^-21 kg·m/s

Therefore, the mass of the deuteron is 3.3435 × 10^-27 kg, and its momentum is -1.1723 × 10^-21 kg·m/s.

Physics

tomatoes are being thrown horizontally off the top of a building 50.0 meters above the ground at 3.00 m/s. How far will the tomatoes travel horizontally by the time it hits the ground? Use significant figures, and estimate g to be equal to 9.81 m/s^2

Step-by-step answer

P Answered by PhD

Answer:

9.6 meters

Step-by-step explanation:

Time taken by the tomatoes to each the ground

using h = 1/2 g t^2

t^2 = 2h/g = 2 x 50/ 9.8 = 10.2

t = 3.2 sec

horizontal ditance = speed x time = 3 x 3.2 = 9.6 meters

Physics

a screw has a head diameter of 0.812 m and a thread width of 0.318 cm. What is the ideal mechanical advantage?

Step-by-step answer

P Answered by PhD

The question specifies the diameter of the screw, therefore the IMA of this screw is 0.812? / 0.318 = 8.02

Physics

A puck moves 2.35 m/s in a -22.0° direction. A hockey stick pushes it for 0.215 s, changing its velocity to 6.42 m/s in a 50.0° direction. What was the magnitude of the acceleration?

Step-by-step answer

P Answered by PhD

Answer:
7.25 secs.

Explanation:
First find the distance it takes to stop
s = [v^2-u^2]/2a = 0^2 - 8.7^2/2[-2.4] = 8.7^2/4.8
Next find the time it takes to go that distance , s = ut +[1/2] at^2
8.7^2/4.8 = 8.7t +[1/2] [ -2.4]t^2 , rearrange and
t^2 -[8.7/1.2]+ 8.7^2/[(1.2)(4.8)]=0 complete the square
[t - (8.7/2.4)]^2=0
t = 8.7/2.4 = 3.625 secs
At this stage the deceleration will push the object back in the direction it came from for another 3.625 secs when it will be 8.7 m/s again
Total time , T =2t = 7.25 secs.

Note:
The term differential is used in calculus to refer to an infinitesimal (infinitely small) change in some varying quantity. For example, if x is a variable, then a change in the value of x is often denoted Δx (pronounced delta x). The differential dx represents an infinitely small change in the variable x.

Physics

compare the momentum of a 6,300 kg elephant walking 0.11 m/s and a 50-kg dolphins swimming 10.m/s

Step-by-step answer

P Answered by PhD

First sum applied the Newton's second law motion: F = ma
Force = mass* acceleration
This motion define force as the product of mass times Acceleration (vs.Velocity). Since acceleration is the change in velocity divided by time,
force=(mass*velocity)/time
such that, (mass*velocity)/time=momentum/time
Therefore we get mass*velocity=momentum
Momentum=mass*velocity
Elephant mass=6300 kg; velocity=0.11 m/s
Momentum=6300*0.11
P=693 kg (m/s)
Dolphin mass=50 kg; velocity=10.4 m/s
Momentum=50*10.4
P=520 kg (m/s)
The elephant has more momentum(P) because it is large.

Physics

An electrical kettle supplies 20,000j of energy to heat 0.5kg of water. What is the temperature change? The specific heat capacity of water is 4200j/kg.

Step-by-step answer

P Answered by PhD

The change in temperature is 9.52°CExplanation:Since, the heat supplied by the electric kettle is totally used to increase the temperature of the water.Thus, from the law of conservation of energy can be stated as:Heat Supplied by Electric Kettle = Heat Absorbed by WaterHeat Supplied by Electric Kettle = m C ΔTwhere,Heat Supplied by Electric Kettle = 20,000 JMass of water = m = 0.5 kgSpecific Heat Capacity of Water = C = 4200 J/kg.°CChange in Temperature of Water = ΔTTherefore,20,000 J = (0.5 kg)(4200 J/kg.°C) ΔTΔT = 20,000 J/(2100 J/°C)ΔT = 9.52°C

Physics

Jordan lifts a 100-kilogram barbell from the floor to a height of 2.0 meters in 1.5 seconds. The amount of power he generates is about ____ watts.

Step-by-step answer

P Answered by PhD

Weight of barbell (m) = 100 kg
Uplifted to height (h) = 2m
Time taken= 1.5 s
Work done by Jordan = potential energy stored in barbell = mgh
= 100×2×9.8
= 1960J
Power = energy/time
= 1960/1.5
1306.67watts

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