Calculating Final Speed of 2.00kg Block of Ice Sliding Down Inclined Plane

[EvanQ]

Homework Statement

A block of ice with mass 2.00kg slides 0.750m down an inclined plane that slopes downward at an angle of 36.9degrees below the horizontal.

f the block of ice starts from rest, what is its final speed? You can ignore friction.

Homework Equations

F=ma, trig equations.

The Attempt at a Solution

not really sure how to tackle this one.
i have initial velocity of 0, angle, mass and distance, but i can't figure out how to tie it all together.

should i be tackling it one dimension at a time? seeing as i know the vertical acceleration and angle?

 

[mgb_phys]

Find the component of the downward force (weight) in the direction of the slope.
Then just f=ma to get the acceleration and v^2 = u^2 + 2as to get final speed.

Or from conservation of energy. Find the vertical distance equivalent to 0.75m at 36.9deg
then use PE = mgh = KE = 1/2 mV^2

 

[EvanQ]

sweet thanks heaps.
used the conservation formula and got 2.97m/s which was correct.

 

[mgb_phys]

My tip is to always use energy conservation if you can. It's a lot simpler than getting all the forces in the right directions and less prone to errors.

 

[rootX]

I always use that work-energy equation. (Assuming that there's nothing like potential energy)

I guess, energy conservation can sometimes put you in trouble.