The pregalactic blobs started with masses comparable to big globular clusters
Indicate whether the statement is true or false
TRUE
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Estimate the time required to heat the center of a 1.5-kg roast in a 163°C oven to 77°C. State your assumptions carefully and compare your results with cooking instructions in a standard cookbook.
GIVEN
FIND
The time required to heat the roast
ASSUMPTIONS
SKETCH
A radioactive sample has an activity R. For which of the following changes would the activity remain unchanged?
a. The number of radioactive nuclei in the sample is doubled. b. The half-life of the radioactive nuclei is doubled. c. The decay constant is doubled. d. A time period equal to two half-lives is allowed to elapse. e. All of the above changes result in a change in the activity.
The observed temperature difference between the northern and southern hemispheres of Uranus:
A) is dozens of Kelvins. B) is hundreds of Kelvins. C) varies greatly. D) is about 10 Kelvin.
When monochromatic X-rays are scattered by a material, the wavelength of the scattered radiation does not depend upon
A) the scattering angle. B) mass of the interacting particle. C) incident wavelength. D) the type of atom.