- #1
Hockey07
- 6
- 0
Homework Statement
This was an exam question that one of my friends recently had.
Two horizontal forces act on a 32.5kg object. The first force has a magnitude of 210N and points in the direction 40.0 degrees East of North. The second force has a magnitude of 350N and points in the direction 20.0 degrees North of West.
What is the magnitude of the acceleration of the object?
Homework Equations
[itex]\Sigma F = ma[/itex]
The Attempt at a Solution
We know how to solve this problem, but the correct answer on the exam was 10.5 [itex]\frac{m}{s^{2}}[/itex]
The issue with this problem is that we believe it's very vaguely worded.
We solved the problem by doing:
[itex]\Sigma Fx = -350cos(20) + 210sin(40) = 32.5a_{x}[/itex]
[itex]\Sigma Fy = 350sin(20) + 210cos(40) - 32.5(9.81) = 32.5a_{y}[/itex]
Then the magnitude of the acceleration would be the square root of the sum of the squares of the acceleration components.
Neglecting gravity and using [itex]\Sigma Fy = 350sin(20) + 210cos(40) = 32.5a_{y}[/itex] yields the correct answer on the exam. Neither of us thought to assume that gravity just disappears (because why would it?)
What do you think - vague question or not?