1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
laila [671]
3 years ago
12

A skier has an acceleration of 2.5 m/s2. How long does it take her to come to a complete stop from a speed of 18 m/s? A. 3.4 s B

. 7.2 s C. 15.5 s D. 0.14 s
Physics
1 answer:
noname [10]3 years ago
6 0
The question is defective. If her acceleration is 2.5 m/s/s, then her speed is 2.5 m FASTER each second, and she will never stop.
You might be interested in
7. A force of 100 N acting on a body gives it a speed of 200 m/s in 2
alekssr [168]

Answer:

Choice a. 1 kg, assuming that all other forces on the object (if any) are balanced.

Explanation:

By Newton's Second Law,

\displaystyle a = \frac{\Sigma F}{m},

where

  • a is the acceleration of the object in \text{m}\cdot\text{s}^{-2},
  • \Sigma F is the net force on the object in Newtons, and
  • m is the mass of the object in kilograms.

As a result,

\displaystyle m = \frac{\Sigma F}{a}.

Assume that all other forces on this object are balanced. The net force on the object will be 100\;\text{N}. The net force is constant. Acceleration should also be constant and the same as the average acceleration in the two seconds.

<h3>What is the average acceleration of this object?</h3>

\displaystyle \begin{aligned}\text{Acceleration} &= \text{Average Acceleration}=\frac{\text{Change in Velocity}}{\text{Time Taken}}\end{aligned}.

\displaystyle {a} = \frac{200\;\text{m}\cdot\text{s}^{-1}}{2\;\text{s}}=100\;\text{m}\cdot\text{s}^{-2}.

<h3>Apply Newton's Second Law to find the mass of the object.</h3>

\displaystyle m = \frac{\Sigma F}{a} = \frac{100\;\text{N}}{100\;\text{m}\cdot\text{s}^{-2}} = 1\;\text{kg}.

6 0
4 years ago
Read 2 more answers
An athlete stretches a spring an extra 40.0 cm beyond its initial length. How much energy has he transferred to the spring, if t
notsponge [240]

Answer:

<h2>b) 4230 J </h2>

Explanation:

Step one:

given data

extension= 40cm

Spring constant K= 52.9N/cm

Step two:

Required

the Kinetic Energy KE

the expression to find the kinetic energy is

KE= 1/2ke^2

substituting our data we have

KE= 1/2*52.9*40^2

KE=0.5*52.9*1600

KE= 42320Joules

<u>The answer is b) 4230 J </u>

4 0
3 years ago
Describe how the number of photoelectrons emitted from a metal plate in the photoelectric effect would change if the following o
andrew-mc [135]

Answer:

a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.

b)   λ = c / f

Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted,

c)  threshold energy

        h f =Ф

Explanation:

It's photoelectric effect was fully explained by Einstein by the expression

       Knox = h f - fi

Where K is the kinetic energy of the photoelectrons, f the frequency of the incident radiation and fi the work function of the metal

a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.

b) wavelength is related to frequency

         λ = c / f

Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted, so there is a wavelength from which electrons cannot be removed from the metal.

c) As the work increases, more frequency radiation is needed to remove the electrons, because there is a threshold energy

        h f =Ф

7 0
3 years ago
John walks four kilometers east, two kilometers north as shown in the diagram below. What is John’s displacement
VashaNatasha [74]
Not 100% positive, but i believe 7 km east?
4 0
3 years ago
Read 2 more answers
Suppose an electron and a proton move at the same speed. which particle has a longer de broglie wavelength? suppose an electron
BARSIC [14]
When both particles, the electron and the proton move at the same speed, they may have differences with their de Broglie wavelength, the particle that would have a longer wavelength would be the proton since the wavelength is in direct proportionality with the mass of the particle.
6 0
3 years ago
Other questions:
  • A car accelerates uniformly from rest to a speed of 56.8 km/h (15.8 m/s) in 10 s. find the distance the car travels during this
    8·1 answer
  • Which of the following statement best define tides?
    9·2 answers
  • What happens to the change in the value of the speed as you increased the amount of force applied on your
    5·1 answer
  • Which type of energy is stored in a battery?
    10·2 answers
  • what is it called when a soccer ball accelerates faster than a bowling ball when the same amount of force is applied?
    8·1 answer
  • What is usually true about the relationship between the speed mechanical waves travel and the temperature of the medium?
    11·1 answer
  • If a 15kg object is moving with a velocity of 10m/s, how much kinetic energy does
    10·1 answer
  • Can inserting a resistor in a circuit produce an effect similar to a short circuit?
    5·1 answer
  • A 10kg crate sits at rest on a rough flat surface. Astudent decides to pull the crate by attaching a rope at a 37 degree angle.
    14·1 answer
  • What is radioactivity????​
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!