Question

Use the work-energy theorem to solve. Neglect air resistance in all cases.
(a) A branch falls from the top of a 76.0-m-tall redwood tree, starting from rest. How fast is it moving when it reaches the ground?

(b) A volcano ejects a boulder directly upward 530 m into the air. How fast was the boulder moving just as it left the volcano?

(c) A skier moving at 4.50 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

Answer 1

Work energy theorem is
W=k2-k1

Answer 2

W=mgh=m*9.8*76

Answer 3

Kinetic energy at 76 m height is k1=0

Answer 4

Kinetic energy at just above the ground is
K2=(1/2)*mv^2

Answer 5

So work energy theorem becomes
m*9.8*76=(1/2)*m*v^2
v=?

Answer 6

I wanna help u when u will b online. b,c question

Answer 7

hello sorry I went to sleep

Answer 8

How do i solve that if i dont know what m is?

Answer 9

U hv to cancel m frm both side

Answer 10

Feel free to ask for more clarification

Answer 11

After cancellation m frm both side we can write
9.8*76=(1/2)*v^2

Answer 12

v=?