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**A traditional watch has a second hand 1.5 cm long from the center to the tip.**

**a) What is the speed of the tip of the second hand?**

d = 2Pir

d = 2(3.14)(1.5)

v = d/t

v = 2(3.14)(1.5)/60s

v = 0.157 cm/s

**b) what is the velocity of the tip at 15s? 45s? 60?**

0.157 cm/s (right)

0.157 cm/s (left)

0.157 cm/s (up)

**c) What is the change in velocity between 30s and 45s?**

I'm having trouble with this one. Do I use the pythagorean theorem because one is pointing to the left and one is pointing down.

0.157^2 + 0.157^2 - sq root

v = 0.222 cm/s (sw)

**A student tosses their pen vertically upward with an intial velocity of 3.8 m/s.**

**a) Maximum height**

Vf^2 = Vi^2 + 2ad

0 = 3.8^2 + 2(-9.8)d

d = 0.736735 m

b) How much time will pass before the pen returns to his hand if it is at the same level that he released the pen at?

b) How much time will pass before the pen returns to his hand if it is at the same level that he released the pen at?

d = v2t - 1/2at^2

0= (3.8)(t) - 1/2(9.8)t^2

t = 0.775510 s

c) if the student's hand is 1.5 m above the ground and he misses the pen, with what speed will the pen hit the ground.

c) if the student's hand is 1.5 m above the ground and he misses the pen, with what speed will the pen hit the ground.

0.736735 + 1.5 = 2.236735 m

Vf^2 = Vi^2 + 2ad

Vf^2 = (0) + 2(9.8)(2.236735)

vf = 6.62117 m/s (down)

Can someone please check these over. I would really appreciate it. Thank you.