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

Physics & Space Science

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Cubes of sugar, 1 cm on a side, are placed in water at 25ÂșC. 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?

Physics & Space Science

The focal length of a converging lens is

A. negative B. zero C. positive D. infinity

Physics & Space Science

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?

Physics & Space Science

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:

1.0 2.10 cm/s 3.20 cm/s 4.30 cm/s 5.40 cm/s 6.50 cm/s 7.60 cm/s 8.impossible to determine

Physics & Space Science