Question 1 of 25

an ice skater starts with a velocity 2.25 m/s in a 50.0 degree direction after 8.33s she is moving 4.65 m/s in a 120 degree dire

svetoff [14.1K]

Answer:

$-0.032 m/s^2$

Explanation:

To answer the question, we just need to consider the motion along the horizontal direction.

The component of the initial velocity of the ice skater along the x-direction is:

$u_x = u cos \theta =(2.25)(cos 50^{\circ})=1.45 m/s$

where u = 2.25 m/s is the initial velocity and $50^{\circ}$ is the angle.

The component of the final velocity of the ice skater along the x-direction is

$v_x = u cos \theta =(4.65)(cos 120^{\circ})=-2.33 m/s$

where u = 4.65 m/s is the final velocity and $120^{\circ}$ is the angle.

The acceleration along the x-direction is given by

$a_x=\frac{v_x-u_x}{t}$

where

t = 120 s is the time

Substituting,

$a=\frac{-2.33-(1.45)}{120}=-0.032 m/s^2$

7 0

4 years ago

Sheila did 110 J of work to move a chair 2 m to the right. How much force did Sheila use to move the chair?

Licemer1 [7]

Take 110 and divide it by 2 and there's your answer

4 0

3 years ago

Select the sentences about the physical nature of light that are true. Check all that apply. Check all that apply. Blue light ha

Phoenix [80]

Correct options:

- Blue light has a wavelength of 750 nm, the longest wavelength of visible light, and red has a wavelength of 500 nm. --> FALSE. It's actually the opposite: blue light has a wavelength of approx. 500 nm, while red has a wavelength of 750 nm, the longest wavelength of visible light.

- Light is electromagnetic radiation, a type of energy embodied in oscillating electric and magnetic fields. --> TRUE. Electromagntic radiation is a type of transverse waves, consisting of electric and magnetic fields oscillating perpendicularly to each other.

- The units of frequency are distance per second. --> FALSE. Frequency is measured in Hertz (Hz), which corresponds to 1/seconds ( $s^{-1}$ .

- The more closely spaced the waves, that is, the longer the wavelength, the more energy there is. --> FALSE. The energy of an electromagnetic wave is inversely proportional to the wavelength:

$E=\frac{hc}{\lambda}$

that means, the longer the wavelength, the less energy there is.

- Grass appears green because it reflects primarily the wavelength associated with green light and absorbs the others. --> TRUE. The color of the objects as we see them corresponds to the color they reflect, while all the other colors are absorbed by the object.

- Light in a vacuum travels at 3.00×108mph. --> FALSE. The units are wrong: the speed of light in a vacuum is $3.00\cdot 10^8 m/s$ .

- Electromagnetic radiation can be characterized by wavelength, amplitude, and frequency. --> TRUE. Wavelength is the distance between two consecutive crests, amplitude is the maximum displacement of the wave relative to the equilibrium position, frequency is the number of oscillations per second.

- The presence of a variety of wavelengths in white light is responsible for the way we perceive colors in objects. --> TRUE. White light consists of many different colors, and depending on which of them are absorbed/reflected by the objects, we perceive them in different ways.

7 0

4 years ago

Which of the following should maintain the appropriate temperature and humidity levels and provide closed-loop recirculating: a.

Diano4ka-milaya [45]

If we define each of the systems that are given in the options we will have to:

Air conditioning is the air treatment that modifies its conditions to suit certain needs, i.e., the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioners are also responsible for controlling humidity in closed rooms.

Positive Pressurization is a pressure within a system that is greater than the surrounding environment. Consequently, if there is any leakage of the system with positive pressure, it will leave the surrounding environment. There is no temperature or humidity control here

Ventilation is done by artificially creating depressions or overpressures in air distribution ducts or building areas. The fans are mechanically responsible for increasing the volume flow of air in a system. Moisture is not controlled directly.

Therefore the correct answer is A.

4 0

4 years ago

After giving an intense performance, a confused and disoriented ﬂautist has wandered onto the motorway! They are playing a con

leva [86]

This is a Doppler effect. Generally, if you move to a frequency source, you would detect an increase in frequency and when you move away from a source you would detect a decrease.

For this question, before you pass them, you are actually approaching them, so you would hear a higher frequency than the constant 300 Hz they are playing at.

Using the condensed formula:

f ' = ((v <u>+</u> vd)/(v <u>+</u> vs)) * f

Where: vd = Velocity of the detector.
   vs = Velocity of the frequency source.
   v = Velocity of sound in air.
   f ' = Apparent frequency.
   f = Frequency of source.

v = 343 m/s, vd = detector = 27.8 m/s, vs = velocity of the source =0. (the flautists are not moving).
f = 300 Hz.

There would be an overall increase in frequency, so we maintain a plus at the numerator and a minus at the denominator.

f ' = ((v + vd)/(v - vs)) * f

f ' = ((343+ 27.8)/(343 - 0)) * 300
   = (370.8/343)* 300 = 324.3

Therefore frequency before passing them = 324.3 Hz.

Cheers.

4 0

3 years ago