A non-uniform rod XY of mass 40 kg and length 5.0 m lines on the horizontal ground. Its centre of gravity is 2.0 metres from the end X .Calculate the vertical Force P that will just be sufficient to lift the end Y from the ground. Why would the force P, is applied at the end X not be sufficient to lift the end X from the ground? (g=10.0 ms^-2)

-a plank XY 3.0m long weighing 20 kg and with its centre of gravity 2.0m from the end A carries a load mass 10 kg at the end A. It rests on two support at C and D.

a)Compute the values of the reaction forces R1 R2 at C and D.

b) How far from D ,and on which side of it must the mass of 24 kg placed on the plank so as to make the reactions equal ? ,What are their values.

c)Without this 24kg ,what vertical Force applied at we will just leave the plank clear of D? What is then the reaction at C?

3. on your graph, the data points between the black squares are data for elements with atomic numbers 3 through 9. locate these elements on your periodic table. what term or description would you use to identify these elements with respect to the periodic table?

What is the relationship between atmospheric pressure and the density of gas particles in an area of increasing pressure? (2 points) as air pressure in an area increases, the density of the gas particles in that area decreases. as air pressure in an area increases, the density of the gas particles in that area increases. as air pressure in an area increases, the density of the gas particles in that area remains constant. as air pressure in an area increases, the density of the gas particles in that area increases and decreases in an alternating pattern. 3. which of the following correctly describes a way in which earth's atmosphere interacts with the geosphere? (2 points) it contains gases that living organisms breathe. it contains gases that trap incoming solar radiation. it provides a medium for cycles that provide nutrients to living organisms. it provides a medium for water to move between earth's surface and the air. 4. which of the following is considered a drawback to using wind energy as a source of power? (2 points) wind energy is nonrenewable. wind energy produces large amounts of air pollution. wind turbines can kill birds that fly through the rotors. wind turbines are built too close to major population centers. 5. a meteorologist predicts that the weather in a region will soon change from clear skies to probable thunderstorms. prior to making this prediction, what did the meteorologist most likely observe on a barometer? (2 points) the barometer fell slightly. the barometer fell substantially. the barometer rose slightly. the barometer rose substantially. 6. which of the following do meteorologists not typically use weather balloons to record? (2 points) atmospheric pressure cloud types humidity temperature 7. during which step in the can crush lab did water vapor force air from the can? (2 points) the can was filled nearly to the top with water. the can was placed on the hot stove top burner for several minutes. the can was removed from the hot stove top burner. the can was placed upside-down in the water-filled pan.

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?