Afreight car moves along a frictionless level railroad track at constant speed. the freight car is open on the top. a large load of sand is suddenly dumped into the freight car. what happens to the speed of the freight car?

The added weight of the sand puts more downward pressure on the wheels contacting the rails, which would cause the trains speed to decrease.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.