1. [-/1.81 Points] DETAILS OSCOLPHYS2016 4.3.P.001. MY NOTES ASK YO An 88.0 kg sprinter starts a race with an acceleration of 1.60 m/s. What is the net external force (in N) on him? (Enter the magnitude.) N2. [-/1.81 Points] OSCOLPHYSZO164.3.P.009. ASK YOUR TEACHER Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The rst child exerts a force of 70.0 N, the second a force of 87.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 23.0 kg. (a) What is the system of interest if the acceleration of the child in the wagon is to be calculated? (Select all that apply.) C] the children outside the wagon C] the wagon C] the child in the wagon (b) Draw a free-body diagram, including all forces acting on the system. f A F2 F2 F2 F1 F1 W W O O O W O (c) Calculate the acceleration in m/s2. (Enter the magnitude.) m/s2 (d) What would the acceleration be (in m/s2) if friction were 17.0 N? (Enter the magnitude.) m/s 23. [-/1.81 Points] DETAILS OSCOLPHYS2016 4.4.P.015. MY NOTES ASK YOUR TEACHER What net external force (in N) is exerted on a 1350-kg artillery shell fired from a battleship if the shell is accelerated at 3.00 x 104 m/s? (Enter the magnitude.) IN What is the magnitude (in N) of the force exerted on the ship by the artillery shell? N4. [-l1.81 Points] OSCOLPHYSZO164.4.WA.022. | ASK YOUR TEACHE You hold your physics textbook in your hand. (Assume that no other objects are in contact with the book.) (a) Identify the forces acting on the book. (Select all that apply.) C] book on hand C] hand on book C] floor on book C] earth on book (b) For each force you identied in part (a), indicate the direction. (If a force is not applicable, choose NA.) book on hand hand on book floor on book earth on book (c) Identify the forces acting on your hand. (Select all that apply.) 3 book on hand 3 hand on book 3 floor on hand 3 earth on hand (d) For each force you identied in part (c), indicate the direction. (If a force is not applicable, choose NA.) book on hand hand on book floor on hand earth on hand (e) Identify the forces that form the action-reaction pair as defined by Newton's third law. earth on hand ---Selei:1-__ v hand on book ---Select--- v In each of the diagrams below, one or more external forces act on the indicated system. Which of the forces listed below are the reaction to the external force mentioned? (Select all that apply.) (a) the mower exerts a force D downward on the Earth due to gravitational attraction D downward on the ground due to contact [3 upward and to the left on the handle [3 upward on the Earth due to gravitational attraction D upward on the ground due to contact (b) the Moon exerts a force to the right on the Earth upward on the Earth to the right on the Sun to the left on the Sun to the left on the Earth downward on the Earth the negatively charged electron (labeled e in the diagram) exerts a force C] downward on the Earth C] to the right on the negative plate C] to the left on the negative plate C] upward on the Earth 6. [-/1.81 Points] OSCOLPHYSZO164.5.P.018. ASK YOUR TEACHER What force (in N) does a trampoline have to apply to a 40.0 kg gymnast to accelerate her straight up at 4.80 m/sz? Note that the answer is independent of the velocity of the gymnastshe can be moving either up or down, or be stationary. (Enter the magnitude.) CW 1. 7. [-/1.81 Points] DETAILS OSCOLPHYS2016 4.5.P.019. MY NOTES ASK YOUR TEACHER (a) Calculate the tension (in N) in a vertical strand of spiderweb if a spider of mass 5.00 x 10-5 kg hangs motionless on it. (b) Calculate the tension (in N) in a horizontal strand of spiderweb if the same spider sits motionless in the middle of it much like the tightrope walker in the figure. 5.0 .5.0 T TR T TR The strand sags at an angle of 14.0 below the horizontal. N Compare this with the tension in the vertical strand (find their ratio). tension in horizontal strand tension in vertical strand +8. [-/1.81 Points] DETAILS OSCOLPHYS2016 4.5.WA.028. MY NOTES ASK YOUR TEACHER To move a box you pull on the handle as indicated in the diagram shown below with a constant force F. The mass of the box is m = 8 kg and the angle 0 = 220. What is the magnitude of the normal force? Omg + F cos(0) Omg + F sin(0) Omg + F Omg - F cos(0) Omg Omg - F sin(0)OSCOLPHYSZO16 4.5.WA.035. ASK YOUR TEACHER Tom enlists the help of his friend John to move his car. They apply forces to the car as shown in the diagram. Here F1 = 427 N and F2 = 340 N and friction is negligible. In the diagram below, the mass of the car = 3500 kg, 01 = 25 and 02 = 12\". (Assume the car faces the positive xaxis before the forces are applied.) 9. [-/1.81 Points] (a) Find the resultant force (in N) exerted on the car. magnitude l:] N direction (counterclockwise from the +x-axis) :] (b) What is the acceleration (in m/sz) of the car? magnitude :] m/s2 direction (counterclockwise from the +X-axis) [: 10. [/1.81 Points] - OSCOLPHYSZO164.7.P.O40. ASK YOUR TEACHER A flea jumps by exerting a force of 1.05 x 105 N straight down on the ground. A breeze blowing on the flea parallel to the ground exerts a force of 0.340 x 106 N on the ea. Find the direction and magnitude of the acceleration of the flea if its mass is 5.80 x 107 kg. Do not neglect the gravitational force. (Assume that the breeze blows in the +x-direction and that the +y-direction is up.) magnitude :] m/s2 direction E counterclockwise from the +x-axis 11. [-/1.9 Points] DETAILS OSCOLPHYS2016 4.7.P.046. MY NOTES ASK YOUR TEACHER A basketball player jumps straight up for a ball. To do this, he lowers his body 0.280 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.860 m above the floor. (a) Calculate his velocity (in m/s) when he leaves the floor. m/s (b) Calculate his acceleration (in m/s) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.280 m. m / s 2 (c) Calculate the force (in N) he exerts on the floor to do this, given that his mass is 118 kg. N