- #1
riseofphoenix
- 295
- 2
Two packing crates of masses m1 = 10.0 kg and m2 = 4.80 kg are connected by a light string that passes over a frictionless pulley as in the figure. The 4.80-kg crate lies on a smooth incline of angle 41.0°.
(a) Find the acceleration of the 4.80-kg crate.
QUESTION 1: WHENEVER I'm given TWO things such as m1 and m2, that means I will be taking the SUM of something right in ORDER to find a variable such as "a" (acceleration) or something else, right?
This is what I did...
Mass 1:
Fnet = T1 + (-m1g)
-m1a = T - m1g
Mass 2:
Fnet = T2 + (-m2gsin θ)
QUESTION 2: Why is sin θ being included in THIS equation for mass 2 but not in the equation for mass 1?
m2a = T - m2gsin θ
Subtract mass 2 from mass 1:
Mass 2: m2a = T - m2g[/B]sin θ
Mass 1: -(-m1a = T - m1g)
–––––––––––––––––––––––––––––––––––––
Equation: m2a + m1a = m1g - m2gsin θ
a(m2 + m1) = m1g - m2gsin θ
a = (m1g - m2gsin θ) / (m2 + m1)
a = [ (10)(9.81) - (4.80)(9.81)(sin 41) ] / (4.80 + 10.00)
a = (98.1 - 30.86) / 14.8
a = 67.24 / 14.8
a = 4.54 m/s2
(b) Find the tension in the string.
QUESTION 3: How would I go about solving for this one?
Just plug in a in either of the original mass equations??
Can you please, please, not be vague/abstract in your answer also?
Thank you.
(a) Find the acceleration of the 4.80-kg crate.
QUESTION 1: WHENEVER I'm given TWO things such as m1 and m2, that means I will be taking the SUM of something right in ORDER to find a variable such as "a" (acceleration) or something else, right?
This is what I did...
Mass 1:
Fnet = T1 + (-m1g)
-m1a = T - m1g
Mass 2:
Fnet = T2 + (-m2gsin θ)
QUESTION 2: Why is sin θ being included in THIS equation for mass 2 but not in the equation for mass 1?
m2a = T - m2gsin θ
Subtract mass 2 from mass 1:
Mass 2: m2a = T - m2g[/B]sin θ
Mass 1: -(-m1a = T - m1g)
–––––––––––––––––––––––––––––––––––––
Equation: m2a + m1a = m1g - m2gsin θ
a(m2 + m1) = m1g - m2gsin θ
a = (m1g - m2gsin θ) / (m2 + m1)
a = [ (10)(9.81) - (4.80)(9.81)(sin 41) ] / (4.80 + 10.00)
a = (98.1 - 30.86) / 14.8
a = 67.24 / 14.8
a = 4.54 m/s2
(b) Find the tension in the string.
QUESTION 3: How would I go about solving for this one?
Just plug in a in either of the original mass equations??
Can you please, please, not be vague/abstract in your answer also?
Thank you.