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A 1.7-kg mass starts from rest at point A and moves along the x axis subject to

ID: 1324890 • Letter: A

Question

A

1.7-kg mass starts from rest at point A and moves along the x axis subject to the potential energy shown in the figure below.

(a) Determine the speed of the mass at points B, C, D.


(b) Determine the turning points for the mass. (Select all that apply.)

point A point B point C point D point E

point B      m/s point C      m/s point D      m/s A 1.7-kg mass starts from rest at point A and moves along the x axis subject to the potential energy shown in the figure below. (a) Determine the speed of the mass at points B, C, D. point B m/s point C m/s point D m/s (b) Determine the turning points for the mass. (Select all that apply.) point A point B point C point D point E

Explanation / Answer

The total ME at point A is

E = PE + KE

As it starts from rest, Ke = 0. Thus,

E = PE = 30 J

Thus, on all points here, the total mechanical energy is 30 J, by conservation of mechanical energy.

Thus,

At point B: PE = 5 J ---> KE = 25 J

As v = sqrt(2KE/m),

vB = 5.42 m/s

At point C: PE = 20 J ---> KE = 10 J.

Using the same formula,

vC = 3.43 m/s

At point D: Pe = 15 J ---> KE = 15 J

Using the same formula,

vD = 4.20 m/s


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The turning points are points B, C, D from the figure.

DONE!