# physics

posted by .

A small 5.00kg brick is released from rest 2.00m above a horizontal seesaw on a fulcrum at its center, as shown in the figure below . (radius of horizontal seesaw is 1.6m)

a.)Find the angular momentum of this brick about a horizontal axis through the fulcrum and perpendicular to the plane of the figure the instant the brick is released.

b.)Find the angular momentum of this brick about a horizontal axis through the fulcrum and perpendicular to the plane of the figure the instant before it strikes the seesaw.

• physics -

the answer to part a) is zero. I don't know why right now though. and the answer to part b) would be 45.1 if it was a 4.50kg brick. I also don't remember how I got that answer.

• physics -

For part B:

angular momentum =
m*r*sqrt(2gh), where r=1.6 and h=2

5*1.6*sqrt(2*9.8*2)

• physics -

Part 1. Velocity is 0.
(mass)(velocity)(r) = 0

Part 2:
v= (sqrt (2gh))= (sqrt(2(9.8)(2))=6.26

(mass)(velocity)(r)
(4.5)(6.26)(1.6)= 45.072=45.1

## Similar Questions

1. ### physics

A small 5.00 kg brick is released from rest 3.00 m above a horizontal seesaw on a fulcrum at its center, with a radius of 1.60 m. Find the angular momentum of this brick about a horizontal axis through the fulcrum and perpendicular …
2. ### physics

Two children seat themselves on a seesaw, the one on the left has a weight of 400N whlie the one on the right weighs 300N. The fulcrum is at the midpoint of the seesaw, if the child on the left is not at the end but is 1.5m from the …
3. ### Kinesiology

Joey weighs 77 lb and sits on a seesaw at a distance of 30 inches from the fulcrum. Jenny weighs 67 lb and sits on the opposite side of the seesaw at a distance of 48 inches from the fulcrum. Mikey weighs 30 lb and wants to play but …
4. ### Physics

Two 2.00kg balls are attached to the ends of a thin rod length 50.0cm and negligible mass. The rod is free to rotate about a horizontal axis at the center, without friction. With the rod horizontal, a 50.0 gram glob of putty drops …
5. ### Algebra

Two children balance on opposite ends of a seesaw. One child weighs 45 pounds and the other weighs 38 pounds. The distance between them is 10 feet. What is the distance of each child from the fulcrum (the center balance point of the …
6. ### physics

two children sit at opposite ends of a 60 lb. 10 ft. seesaw which is pivoted at its center one child weighs 50 lbs. and the other 75 lbs. the seesaw is uniform so that its center of gravity is at its geometric center, which also is …
7. ### Physics

39. (Taken from problem 5 at the end of Chapter 9) Look at the children balanced on the see-saw in the figure below. r1 = 1.60 m. The center mass of the seesaw is located 0.16 m to the left of the pivot point. The seesaw board has …
8. ### Physics

Three children are trying to balance on a seesaw. The seesaw is 3.9 m long and pivots about a rock at its center. Louie and Laura are already sitting on opposite ends. If Martha weighs 27 kg, where should she sit so as to balance the …
9. ### Physics

A 10-ft,25lb seesaw is balanced by a little girl with a weight of 50lbs and her father with a weight of 200lbs at opposite ends. How far from the seesaw's center of mass must the fulcrum be placed?
10. ### Physics

A 5 m, 10 kg seesaw is balanced by a little girl(25 kg) and her father(80 kg) at the extreme opposite ends. How far from the seesaw's center of mass must the fulcrum be placed

More Similar Questions