▾ Part C In Part A, you defined the coordinate system to have the positive y direction pointing upward. Give the directions of the normal force i exerted by the ground on the froghopper and the froghopper's weight w using this coordinate system. Give the direction of the normal force followed by the direction of the weight separated by a comma. For instance, if you thought that both were directed downward, you would enter -,-. downward, upward Submit Previous Answers Request Answer Incorrect; Try Again SOLVE Now that you've set up the problem, choose appropriate equations and solve for your unknowns. Part D The jump (the period during which the froghopper exerts a force) has a distinct beginning and ending. Consider the jump to begin at time to = 0 and end at time t. Which of the following variables are given in the question and therefore known? Check all that apply. The time t of the end of the jump The initial speed vo The final speed v at time t The acceleration a during the jump The mass m of the froghopper The magnitude n of the normal force exerted by the ground The magnitude w of the froghopper's weight Submit Previous Answers Request Answer Incorrect; Try Again Part E What is the formula for the magnitude Fnet of the net force on the froghopper during the jump? Let m be the froghopper's mass and g be the magnitude of the acceleration due to gravity. Express your answer in terms of some or all of the variables m, g, and n. View Available Hint(s) Hint 1. Using the free-body diagram In the free-body diagram, the weight of the froghopper points downward (the negative y direction) and the normal force is directed upward (the positive y direction). Recall that the magnitude of weight is just the mass m multiplied by the gravitational acceleration g. Fnet = Ε ΑΣΦ Submit Request Answer ? Problem-Solving Strategy 4.1 Newton's laws SET UP 1. Define your coordinate system. Be sure to draw a diagram showing the positive axis direction. If you know the direction of the acceleration, it's often convenient to take that as your positive direction. If you need to calculate displacements of the moving object, specify the location of the origin of your coordinate system. 2. Be consistent with signs. Once you define the x axis and its positive direction, the components of velocity, acceleration, and force in that direction are also positive. 3. Concentrate on a specific object. Draw a free-body diagram showing all the forces (magnitudes and directions) acting on this object, but do not include forces that the object exerts on any other object. Represent the object as a dot or by a simple sketch. SOLVE 4. Identify the known and unknown quantities, and give each unknown quantity an algebraic symbol. If you know the direction of a force at the start, use a symbol to represent the magnitude of the force. 5. Always check units for consistency. REFLECT 6. Check to make sure that your forces obey Newton's 3rd law. When you can guess the direction of the net force, make sure that its direction is the same as that of the acceleration, as required by Newton's 2nd law. SET UP Before writing any equations, organize your information and draw appropriate diagrams. Part A It is easiest to choose your coordinate system so that the acceleration of the object of interest is in the positive direction. In which direction does the froghopper accelerate? upward downward to the left to the right Submit Part B Previous Answers Correct Now that you've figured out which direction it accelerates, you should draw your coordinate system with the positive y axis pointing upward. Since you are concerned with the froghopper's acceleration, you need to draw a free-body diagram for the froghopper. Which of the following forces should be included on your free-body diagram? • The normal force ₁ exerted by the froghopper on the ground • The normal force 2 exerted by the ground on the froghopper • The weight w of the froghopper 71 only 712 only n₁ and w only 72 and w only 71 and 72 only 1, 2, and w Submit Previous Answers Correct