Forces in 2D Legacy Problem #2 Guided Solution
Problem*
Hector is walking his dog (Fido) around the neighborhood. Upon arriving at Fidella's house (a friend of Fido's), Fido turns part mule and refuses to continue on the walk. Hector yanks on the chain with a 67.0 N force at an angle of 30.0° above the horizontal. Determine the horizontal and vertical components of the tension force.
Audio Guided Solution
Here we are told that Hector is applying a force upon phi dot of 67 Newtons magnitude and the direction is 30 degrees above the horizontal. This force which is at an angle to the horizontal and the vertical has two components. A component could be described as the effect of a force in a given direction. To say this 67 Newtons force has two components means that it has a portion of which is directed in the horizontal direction and a portion of which is directed in the vertical direction. We could determine these horizontal and vertical effects by simply using a sine, cosine, or tangent function of 30 degrees. So what I typically do is I draw a vector arrow that is representing the force and I draw it such that it is tilted 30 degrees above the horizontal and then I draw a horizontal line at the at the very tail of that force that stretches out horizontally and I draw it for a while and then coming down from the arrowhead of that 67 Newton force I draw another vertical line that comes down to meet that horizontal line that I draw. When I do that I have a right triangle and within that right triangle there is a 30 degree angle between the 67 Newtons and the horizontal at the tail of that 67 Newton vector. So if 67 Newtons is the hypotenuse of that right triangle I can use the sine value to determine the side opposite and I can use the cosine value to determine the side adjacent to that 30 degree angle. And so to get the horizontal side which is the side adjacent I would go 67 times the cosine of 30 degrees and to get the opposite side which is the vertical side I would go 67 times the sine of 30 degrees and that will get me my horizontal and my vertical component of that 67 Newton force.
Solution
\(F_x = \units{58.0}{N}\)
\(F_y = \units{33.5}{N}\)
Habbits of an Effective Problem Solver
- Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
- Identify the known and unknown quantities in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., \(m = \units{1.25}{kg}\), \(µ = 0.459\), \(v_o = \units{0.0}{\unitfrac{m}{s}}\), \(θ = 41.6°\), \(v_f = \colorbox{gray}{Unknown}\).
- Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
- Identify the appropriate formula(s) to use.
- Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
Read About It!
Get more information on the topic of Forces in 2D at The Physics Classroom Tutorial.