gAn Olympic diver is on a diving platform 5.40 m above the water. To start her dive, she runs off of the platform with a speed o
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Answer:
3.0 seconds
Explanation:
We can solve the problem by considering the horizontal motion of the ball only. In fact, the ball moves by uniform motion (constant speed) along the horizontal direction, since there are no forces acting in this direction. The horizontal speed of the ball is given by:
and it does not change during the motion.
We also know that the ball travels a horizontal distance of d = 60 m, so we can find the time it takes to cover the distance by using the equation:
Refer to the diagram shown.
There are twelve 5-minute divisions.
Each 5-minute division is equal to 360°/12 = 30°.
By convention, angles are measured counterclockwise from the positive x-axis.
The angular position of the minute hand at 2:55 is
θ = 90° + 30° = 120°
Because 360° = 2π radians, therefore
θ = (120/360)*2π = (2π)/3 radians = 2.0944 radians
Answer: (2π)/3 radians ofr 2.0944 radians.
There are twelve 5-minute divisions.
Each 5-minute division is equal to 360°/12 = 30°.
By convention, angles are measured counterclockwise from the positive x-axis.
The angular position of the minute hand at 2:55 is
θ = 90° + 30° = 120°
Because 360° = 2π radians, therefore
θ = (120/360)*2π = (2π)/3 radians = 2.0944 radians
Answer: (2π)/3 radians ofr 2.0944 radians.
(a)
Wien's displacement law is summarized by the equation
where
is the peak wavelength
is Wien's displacement constant
T is the absolute temperature at the surface of the star
For an O-type star, we have
T = 40,000 K
Therefore, its peak wavelength is
(b) Ultraviolet
We can answer this part by looking at the wavelength range of the different parts of the electromagnetic spectrum:
gamma rays
X-rays 1 nm - 1 pm
ultraviolet 380 nm - 1 nm
visible light 750 nm - 380 nm
infrared
microwaves 1 mm -
radio waves > 1 mm
The peak wavelength of this star is
Therefore, it falls in the ultraviolet region.
(c) No
The Keck telescopes is actually a system of 2 telescopes in the Keck Observatory, located in Mauna kea, Hawai.
The two telescopes, thanks to several instruments, are able to detect much of the electromagnetic radiation in the visible ligth and infrared parts of the spectrum. However, they are not able to detect light in the ultraviolet region: therefore, they cannot observe the star mentioned in the previous part of the problem.