While bob is demonstrating the gravitational force on falling objects to his class, he drops an 1.0 lb bag of feathers from the top of the science building. determine the distance the bag has traveled after falling for 1.5 seconds assuming it has reach free fall and given the gravitational acceleration of 9.8 m/sec2. a) 7.4 m b) 11 m c) 15 m d) 22 m

As per the question the mass of the bag of feathers is given as 1.0 lb.

Hence mass(m) = 1.0 lb

The bag is under free fall.Hence the acceleration with which the bag falls towards the centre of Earth is nothing else except the acceleration due to gravity.

Hence acceleration a=g=9.8 m/s^2

The time(t)given in the question=1.5 s

We are asked to calculate the distance travelled by the bag at that instant.

Let the air resistance is very small which is neglected.

From equation of kinematics we know that-

       S=ut +0.5at^2

Here S is the distance travelled,u is the initial velocity and a is the acceleration.

As the motion is under free fall,the initial velocity (u)= 0

Hence distance travelled

                S= 0×1.5+{0.5×(-9.8)×(1.5)^2}

                  =0-11.025 m

                  = -11.025 m

                  =  -11.0 m

Here negative sign only indicates vertical downward motion .

Taking only magnitude the distance travelled S =11 m.

Hence the correct option is B.

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

-it's clean and sustainable

-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

-almost everywhere, the shallow ground or upper 10 feet of the earth's surface maintains a nearly constant temperature between 50° and 60°f (10° and 16°c)

-geothermal heat pumps can tap into this resource to heat and cool buildings

-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

-in the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system

-in the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger

-the heat removed from the indoor air during the summer can also be used to provide a free source of hot water