Answer: The correct answer is option B.
Explanation:
Mass of the sled = 10 kg
Initial speed of the sled = 2 m/s
Kinetic energy of the sled = 

Work done by the sled = 20 joules
The work done by the friction will be in opposite direction and equal to the magnitude of the work done of the sled that - 20 J.
Hence, correct answer is option B.
The eaths radius is the correct answer, if you need proof look at nasa's website
Answer:c-The gravitational effect when spacecraft flies close to the asteriod
Explanation:
Gravitational effect on the spacecraft gives an estimate that how big is the asteroid by experiencing its gravitational pull.
The amount of extra thrust required to maintain the trajectory of the spacecraft during its motion hints at the scientist about the size of the asteroid.
Gravitational pull is directly proportional to the mass of object so greater the mass, greater will be the pull.
Divide CFU of Dilution. Divide the CFU of the dilution (the number of colonies you counted) by the result from step 4. For this example, you work out 46 ÷ 1/1000, which is the same as 46 x 1,000. The result is 46,000 CFU in the original sample.