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vova2212 [387]
3 years ago
8

A skateboarder traveling at 7.0 meters per second rolls to a stop at the top of a ramp in 3.0 seconds. What is the skateboarder’

s acceleration?
*Please only answer if you know - and ABSOLUTLEY NOOOOOOOO LINKS*
Thank you! :)
Physics
1 answer:
ki77a [65]3 years ago
8 0

Answer:

-2.33 m/s²

Explanation:

The computation of the skateboarder’s acceleration is shown below;

Acceleration means the change in velocity per unit with respect to time.

In the given case, the initial velocity is 7 m/s.

As in the question it is mentioned that  it comes to a stop, so the final velocity would be zero.

And, The time elapsed is 3 seconds.

Now the following equation should be used  

a = (v,final - v,initial) ÷ t

=  (0 - 7)/3

= -2.33 m/s²

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Is 51/17 a rational number
mylen [45]

Answer:

Yes.

Explanation:

51/17 is a rational number because "A number is considered a rational number if it can be written as one integer divided by another integer."

6 0
3 years ago
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A black lift of amber is placed in water and a laser beam travels from the water through the amber. The angle of incidence is 35
horsena [70]

Answer:

Explanation:

refractive index of ember = sin of angle of incidence / sin of angle of refraction

= sin 35 / sin24

= .5735 / .4067

= 1.41

This is refractive index of ember with respect to water

refractive index of ember with respect to water

= wμe = μe / μw

μe = wμe x  μw

= 1.33 x 1.41

= 1.87

refractive index of ember with respect to air = 1.87 .

6 0
3 years ago
Infrared waves from the sun are what make our skin feel warm on a sunny day. If an infrared wave has a frequency of 3.0 x 1012 H
djyliett [7]

Answer:

The wavelength of the infrared wave is <u>0.0001 m</u>.

Explanation:

Given:

Frequency of an infrared wave is, f=3.0\times 10^{12}\ Hz

We know that, infrared waves are electromagnetic waves. All electromagnetic waves travel with the same speed and their magnitude is equal to the speed of light in air.

So, speed of infrared waves coming from the Sun travels with the speed of light and thus its magnitude is given as:

v=c=3.0\times 10^8\ m/s

Where, 'v' is the speed of infrared waves and 'c' is the speed of light.

Now, we have a formula for the speed of any wave and is given as:

v=f\lambda

Where, \lambda \to \textrm{Wavelength of infrared wave}

Now, rewriting the above formula in terms of wavelength, \lambda, we get:

\lambda=\dfrac{v}{f}

Now, plug in 3.0\times 10^8 for 'v', 3.0\times 10^{12} for 'f' and solve for  \lambda. This gives,

\lambda=\frac{3.0\times 10^8}{3.0\times 10^{12}}\\\\\lambda=0.0001\ m

Therefore, the wavelength of the infrared wave is 0.0001 m.

5 0
3 years ago
A 13,000 kg helicopter accelerates upward a 0.5 m/s^2 while lifting a 2000 pound car. to the nearest newton, what is the lift fo
Vinil7 [7]

Lift force exerted by the air on the rotors=143244 N

Explanation:

we use Newtons second law

F- (M+m)g=(M+m)a

F= lift force

m= mass of helicopter= 13000 Kg

M= mass of car= 2000 lb=907.2 kg

a= acceleration= 0.5 m/s²

g= acceleration due to gravity

F- (M+m)g=(M+m)a

F=(M+m)(a+g)

F=(13000+907.2)(0.5+9.8)

F=143244 N

8 0
3 years ago
Calculate the change in length of a 90.5 mm aluminum bar that has increased in temperature by from -14.4 oC to 154.6 oC
nignag [31]

Answer:

 ΔL = 3.82 10⁻⁴ m

Explanation:

This is a thermal expansion exercise

          ΔL = α L₀ ΔT

          ΔT = T_f - T₀

where ΔL is the change in length and ΔT is the change in temperature

Let's reduce the length to SI units

          L₀ = 90.5 mm (1m / 1000 mm) = 0.0905 m

let's calculate

          ΔL = 25.10⁻⁶ 0.0905 (154.6 - (14.4))

          ΔL = 3.8236 10⁻⁴ m

     

using the criterion of three significant figures

          ΔL = 3.82 10⁻⁴ m

5 0
3 years ago
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