Which of the following is thought to be a black hole?
a. Gleise 229B
b. Sirius B
c. Orion Nebula
d. Cygnus X-1
d
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Cubes of sugar, 1 cm on a side, are placed in water at 25ºC. Estimate the time before the lumps have dissolved; that is, when the sugar concentration at the lump is 10% by weight. Assume that the diffusivity of sugar into water is 6.9 x 10^-10m^2/s, the convective mass transfer coefficient is 6.4 x 10^-6m^2/s, and the self-diffusivity of sugar is 1 x 10^-5m^2/s. The density of sugar may be taken as 1500 kg/m^3.
What will be an ideal response?
The focal length of a converging lens is
A. negative B. zero C. positive D. infinity
A 500?g block traveling at 60 cm/s slides onto a 1?kg cart as shown. The block stops sliding before reaching the end of the cart
The final speed of the cart is closest to:
David stands 2.5 meters in front of a plane mirror
(a) How far from David is David's image in the mirror? (b) If David moves away from the mirror at 1.5 m/s, how fast are David and his image moving apart from each other? (c) If David is 180. cm tall, how tall is his image in the mirror?