Atwood Machine: Find m1's Descent and Velocity

[physics_geek]

Homework Statement

In the Atwood machine shown below, m1 = 2.00 kg and m2 = 7.50 kg. The masses of the pulley and string are negligible by comparison. The pulley turns without friction and the string does not stretch. The lighter object is released with a sharp push that sets it into motion at vi = 2.80 m/s downward.
(a) How far will m1 descend below its initial level?

(b) Find the velocity of m1 after 1.80 s.

Homework Equations

f= ma
vf^2 = v^2 + 2ad

The Attempt at a Solution

i think for part a u use the equation i put above..but i don't know how to figure out acceleration...but i think its splitted between the two objects

 

[alphysicist]

Hi physics_geek,

Homework Statement

In the Atwood machine shown below, m1 = 2.00 kg and m2 = 7.50 kg. The masses of the pulley and string are negligible by comparison. The pulley turns without friction and the string does not stretch. The lighter object is released with a sharp push that sets it into motion at vi = 2.80 m/s downward.
(a) How far will m1 descend below its initial level?

(b) Find the velocity of m1 after 1.80 s.

Homework Equations

f= ma
vf^2 = v^2 + 2ad

The Attempt at a Solution

i think for part a u use the equation i put above..but i don't know how to figure out acceleration...but i think its splitted between the two objects

To find the acceleration, start by drawing force diagrams for each of the objects. Using \sum F = m a for each of the diagrams then gives two equations with two unknowns.

(You can also use an energy appoach here.)

 

[thisismysn230]

Use the formula a= (gm1 + gm2)/(m2+m1) to find the acceleration then use the formula V^2=-2ad to find the distance. Bada bing bada boom!
Im still workin on the second part unfortunately...