1. A ball is projected up an incline and rolls around a track as shown above. At which two labelled points is the work done by the gravitational force on the ball not negative? Select two answers. 2. A single force is exerted on an object in the x
direction. Shown is a graph of that force and the displacement of the object in that direction. What amount of work is done for the 30 m shown?
a. 30J
b. 45J
c. 50J
d. 60J

3. An object of mass, m, hanging from the end of a
light string is initially at rest. It is lowered by the string a distance s and reaches a speed vf. How much work was done on the object by the string?

A single constant force is exerted on an object. The graph describes the object's energy. How much work was done to increase the speed of the object from 1.0 m/s to 3.0 m/s?
A. 1.5J
B. 2.0J
C. 4.0J
D. 4.5 J

5. A block of mass m initially at rest is pulled along
a plane inclined at 30° with the horizontal. At a height h it has kinetic energy Kf. The coefficient of friction with the incline is J. Which of the following correctly represents the net work done on the block?

An object of mass, mn, is attached to a spring hanging from the ceiling as shown. It is initially sup ported so the spring is unstretched. The object is released and falls. Which of the following correctly describes the kinetic energy of the object when it has fallen a distance h below the starting point?

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

bacteria that live on the ocean floor are sustained by phytoplankton. phytoplankton, microscopic marine photosynthetic organisms, have a vastly significant role to play not only in the marine food web of which they’re part of, but also on a more global scale. despite their infinitely small size in comparison to other marine organisms, these tiny creatures occupy an immensely important ecological niche: they are the foundation of the marine food web, and as primary producers, play key roles in supporting all other organisms in the marine environment, as well as in the regulation of the earth’s climate through the sequestration of carbon, oxygen production, and other related processes. phytoplankton account for roughly half of all global primary productivity; therefore, their significance extends far beyond the marine environment alone. there is an intriguing sense of irony in the realization that these tiny living beings that often live out their existence unnoticed and undetected by the rest of the world, have such a far-reaching impact on the lives of virtually all other living organisms on the planet, particularly on those in the marine environment. the world that we have become accustomed to has been and is continuously shaped by the workings of these miniscule yet vital “plants of the sea”.

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