Use the work-energy theorem to solve each of these problems. You can use Newton\

Question

Use the work-energy theorem to solve each of these problems. You can use Newton's laws to check your answers. Neglect air resistance in all cases.

(a) A branch falls from the top of a 81.0-m-tall redwood tree, starting from rest. How fast is it moving when it reaches the ground? . m/s

(b) A volcano ejects a boulder directly upward 545 m into the air. How fast was the boulder moving just as it left the volcano? m/s

(c) A skier moving at 4.60 m/s encounters a long, rough horizontal patch of snow having coefficient of kinetic friction 0.220 with her skis. How far does she travel on this patch before stopping? m

(d) Suppose the rough patch in part (c) was only 2.90 m long? How fast would the skier be moving when she reached the end of the patch? m/s

(e) At the base of a frictionless icy hill that rises at 25.0° above the horizontal, a toboggan has a speed of 11.5 m/s toward the hill. How high vertically above the base will it go before stopping?

Explanation / Answer

conserving energy

a)

mgh = 0.5mv^2

v = sqrt (2gh)

v = 39.844m/s

b)

0.5mv^2 = mgh

v = sqrt (2gx 545)

v = 103.35m/s

c)

0.5mv^2 = umgx S

S = V^2/2ug

S = 4.907m

d)

0.5m (V^2 -u^2) = -umgx 2.9

V = 2.94m/sec

e)

0.5mV^2 = mgh

h = 6.747m

Related Questions

Navigate

• Browse (All)
• Browse U
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.