Preview

Physics Problem

Good Essays
Open Document
Open Document
1726 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Physics Problem
SAMPLE PROBLEMS: 111-SET #1 VECTOR ADDITION, SUBTRACTION

01-1

1). A man is able to row a boat at 3 mph in still water. If he rows his boat pointed straight across a river with a current of 4 mph, what is his net velocity? If the river is 0.5 miles wide, at what point will he land on the other side? Solution: The first step in problem solving is to identify the problem type. In this problem we are asked for a ‘net velocity.’ Since velocities behave as vectors, then we have a vector addition problem. A figure is drawn with the vectors indicated. Here vb is the boat’s velocity (still water), vr is the river’s velocity, and vnet is the resultant (net) of these two velocities. The vector equation pertinent to the problem is: vnet = vb ⊕ vr .

vb vr y x

v net

A coordinate system is selected as shown. Note that all vector problems are calculated by means of the component method (rectangular resolution), and hence a specified coordinate system is essential. Since our vector space is 2-dimensional, the vector equation above reduces to two scalar equations. One for each of the necessary components. We calculate the components of the vectors to be added. For the coordinate system selected we have: vnet x = vbx + vrx = 3 + 0 = 3 mph ; vnet y = vby + vry = 0 + 4 = 4 mph The answer for the net velocity can be specified in two equivalent ways. One way is to specify the two components for the net velocity (as done above). The second method is to state the magnitude and direction for vnet. |vnet| =

3 + 4 2 = 25

= 5 mph.

The direction is given by an angle. From the figure we see we have a 3,4,5 right triangle. Hence, we can determine θ by any of the following: sin θ = vy/vnet = 4/5 cos θ = vx/vnet = 3/5 tan θ = vy/vx = 4/3 θ = 530 θ = 530 θ = 530

3 θ x

The equivalent answer for vnet is: 5 mph at 530 downstream.

4 y v net

01-2 The problem also asks at what point he will reach the other side of the river. Since all velocities in the

You May Also Find These Documents Helpful

  • Satisfactory Essays

    Week 2 PH220

    • 359 Words
    • 2 Pages

    Net velocity = 3 cos 55°= 1.72, 3 sin 55°-2 = .46  1.72 + .46 = 1.78 m/s…

    • 359 Words
    • 2 Pages
    Satisfactory Essays
  • Powerful Essays

    1.a Up, up, and away [15] A balloonist can’t resist throwing a drink to another balloonist. The ‘thrower’ is moving at v = -15j m/min while the ‘catcher’ is moving at v = 15j m/min. At the instance the former throws the drink the ‘catcher’ is at (3i – 10j) m from the ‘thrower’. If the throw is horizontal, at what speed does the drink need to be thrown to be caught?…

    • 1252 Words
    • 6 Pages
    Powerful Essays
  • Better Essays

    Physics Midterm Study Guide

    • 3632 Words
    • 15 Pages

    a.Calculate the velocity of the ship on the river. vwater = (-5, 0)m/s, v = v0 + vwater =Answer (7, 6) m/s…

    • 3632 Words
    • 15 Pages
    Better Essays
  • Satisfactory Essays

    12. A raft of mass 180 kg carries two swimmers of mass 50. kg and 80. kg. The raft is initially floating at rest. The two swimmers simultaneously dive off opposite ends of the raft, each with a horizontal velocity of 3 m/s. Determine the final velocity and direction the raft.…

    • 693 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    (3) drawing vectors showing displacement, velocity, and acceleration and their x and y components at different times.…

    • 1266 Words
    • 4 Pages
    Good Essays
  • Satisfactory Essays

    1. A boy is whirling a yo-yo above his head in a counter-clockwise direction. At the exact moment shown at left, he lets go of the string. In which direction will the yo-yo travel? Draw an arrow on the image to show the yo-yo’s direction.…

    • 1444 Words
    • 6 Pages
    Satisfactory Essays
  • Satisfactory Essays

    chen (azc96) – Assignment 6 - Electricity – schultz – (WVSPR2011APB01) This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points An object with a charge 3 C and a mass 0.4 kg accelerates from rest to a speed of 19 m/s.…

    • 984 Words
    • 4 Pages
    Satisfactory Essays
  • Powerful Essays

    Biology Project

    • 2251 Words
    • 10 Pages

    2.Add all the times up and divide by 100 then calculate the velocity using this equation V= D/T D=distance T=time.…

    • 2251 Words
    • 10 Pages
    Powerful Essays
  • Powerful Essays

    Physics Quiz

    • 934 Words
    • 4 Pages

    2. If you double the current through an inductor, the energy stored in the associated magnetic field increases by a factor of _____.…

    • 934 Words
    • 4 Pages
    Powerful Essays
  • Satisfactory Essays

    4 1

    • 331 Words
    • 2 Pages

    4. The diagram below shows three islands in Florida Bay. You rent a boat and plan to visit each of these remote islands. If you are on island B, on what bearing should you navigate to go to island C?…

    • 331 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Chapter 1 Lab

    • 606 Words
    • 2 Pages

    2) Which color vector (arrow) represents velocity and which one represents acceleration? How can you tell?…

    • 606 Words
    • 2 Pages
    Good Essays
  • Good Essays

    What?

    • 3646 Words
    • 15 Pages

    What do you do with any vector that is not on either the x or y axis?-break it up into x and y components using trig, add up the components.…

    • 3646 Words
    • 15 Pages
    Good Essays
  • Good Essays

    Physics

    • 590 Words
    • 3 Pages

    7)Two cars are moving at constant velocity to the right. At time = 0, car A is 25 m ahead of car B. Car A has a velocity of 20 m/s and car B has a velocity of 25 m/s. Draw a motion map for the two cars up to time = 10 sec. Explain how you can determine when car B catches up to car A.…

    • 590 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Physics Quiz

    • 3581 Words
    • 15 Pages

    A 10-kg bowling ball moving at 4 m/s bounces off a spring at about the same speed that it had before bouncing. What is the change in momentum of the bowling ball?…

    • 3581 Words
    • 15 Pages
    Good Essays
  • Good Essays

    Year 10 Physics

    • 330 Words
    • 2 Pages

    For example, if you have a car that has travelled 50km in 20 minutes the average speed would be 1km/2.5min.…

    • 330 Words
    • 2 Pages
    Good Essays

Related Topics