Physics Lab (Online Simulation) Physics Lab (Online Simulation) Physics Lab (Online Simulation) RAMP: FORCES AND MOTION Objective: If the box moves with constant velocity, the net force is zero. Note the general equation and the This activity is intended to enhance your physics education. We offer it as a virtual lab online. subsequent two equations about the state of motion described and the figure above Mechanics We think it will help you make connections between predictions and conclusions, concepts and Student Name: actions, equations, and practical activities. We also think that if you give this activity a chance, it (1) will be fun! This is an opportunity to learn a great deal. Answer all questions as you follow the Student ID: procedure in running the simulation. Horizontal surface: Ff = umg ( 2 ) Familiarize yourself with The Ramp: Forces and Motion simulation using different scenarios as Inclined surface: Fr= umg cose (3 ) shown in the figure above. Click a tab at the top to view a scenario. For example, click the Free Body Diagram Simulation Activity #2: Ramp: Forces and Motion Introduction tab, to view the first figure above. In this figure, you can select an object from the O Show @ Hide drop-down menu at the center bottom. You can also drag the box or insert the value in the space Procedure: Open Ramp: Force and Motion Simulation created by the Physics Education Technology Project (PhED) clo The University of Colorado at Boulder http://phet.colorado.edu/ Friction provided for the applied force to move the box. If you want to see the effect of friction and mass http://phet colorado.edu/en'simulation/ramp-forces-and-motion O ke (na friction) of an object on the force applied click the next tab, friction. You can also change gravity using the sliding bar just below the object's mass. If you want to observe graphs that represent what 1. Click the Introduction tab Word you are doing on the box, check the force graphs tab. In doing all of these, you need to a. Select the small crate from the drop-down option. Vectors understand the controls to the right of the simulations. These controls help you where you can b. Change the values of the ramp angle to zero so that the surface is horizontal Adjust the object position to be at 8.0 m. Foroa Vactors hide or show the free body diagram, use the ice, or wood surface, to display force vectors and/or sum of forces, and more controls to specify the object's position and to define the angle of the d. Now, slowly increase the ramp angle until you reach an angle when the small "9am of Forces sum ramp. Once you understand how to operate the simulation, you can predict the results based on crate is about to move. Angle = _ _degree the theoretical background (for example, the basics explained in the introduction below) and Keeping the same angle, what minimum applied force do you need to move the Walls verify it using the simulation. crate up the inclined plane? Drag the small crate along the direction of the inclined plane and observe the changing values of the applied force. Applied force Introduction: More Controls When an object is dragged across a horizontal (or inclined) surface, the force of friction that f. Draw the free-body diagram. Object Pastion -8.0 meters must be overcome by any parallel (to the surface) force (F) depends on the normal force (FD) Switch the small crate with the File cabinet and repeat steps b through f. Compare and the coefficient of friction (). Depending on the situation the normal force can be expressed the angle and the applied forces you found for the small crate. Which quantity -10 D 10 D in different ways. For example, if the force applied is parallel to the surface as shown below, the didn't change its value? If so, why? Hint: Look the given equations. normal force is equal to the weight in the case where the object is on the horizontal surface, and h. Now, change the object to the mysterious object and try to find the angle of the Ramp Angle 390 degrees the normal force is equal to the weight times the cosine of the angle of the inclined in the case of ramp at which the mysterious object is about to move. Angle = _ _degree the inclined surface. Note that the friction changes as the normal force expression changes What is the mass of the mysterious object? Hint: find the applied force by dragging up the inclined plane with constant velocity. Mass = kg 80.0 j- What will be the minimum applied force needed for the mysterious object to Choose an Object move along the horizontal plane? Small Crate k. Check your answers in steps d and e theoretically 2. Click the Friction tab. ()) @ on Oct a. Adjust the static and kinetic coefficients of frictions to 0.4 and 0.3 respectively for Reset Al a 100 kg object located on Earth mgsine b. Let the ramp angle be 30 degrees. sosour c. If the object starts sliding down the inclined plane from the 8.0 m position, how Small Crate 100 kg 1 0.3 1/20.5 Ff mg far it can travel along the horizontal plane? Ax = m Espe File Cabinet d. If you want the object to cover 1.0 m on a horizontal plane after sliding down the 50 kg H =0.2 inclined plane from the 8.0 m position, you will adjust the coefficient of friction Sleepy Log or the angle of the ramp. 25 kg 1, =0.5 u,=0.5 i. Keeping the angle at 30 degrees, find the static and kinetic coefficients of Refrigerator mg friction. 200 kg H. =0.2 w.=0.5 Textbook 10 kg , =0.2 1,=0.4 Mystery Object8. Realizing that there is also a force parallel (as a component of weight) you must ALSO overcome, what is the TOTAL force you must apply to push the cart up the ramp at a ii. Keeping the static and kinetic coefficients of friction to 0.4 and 0.3, find constant speed? N the ramp angle. 3. Click the Force Graphs tab. a. Check the Freedom, Equity, and Esio boxes b. Using steps a b, and c of procedure 1, and the ramp angle found in step d run the simulation c. What are the values of forces you read from the graphs i. On inclined plane: Fourjo- N, ESAJA_ N ii. On a horizontal surface: N, Eat N. N d. Repeat c using setups a and b of procedure 2. i. On inclined plane: Foreign N, ESAU N On horizontal surface: N, Eat N, N iii. Using distances along the inclined plane and horizontal planes and the respective times from the graph, calculate the average speeds of the crate 1. on the inclined plane: Van m on the horizontal surface: you e. Adjust the ramp angle to 30 degrees, select the sleepy dog, and run the simulation with wood then with ice using the friction control. Using the time information from the graph, and acceleration along the inclined plane, find the speed at the bottom of the inclined plane i. Wood: v=_ m/'s, Ice: =_ m/s Follow-up Questions: 1. As the angle of the ramp is increased, the normal force increases /decreases / remains the same, and the friction force increases /decreases / remains the same. 2. As the angle of the ramp is increased, the force parallel increases /decreases / remains the same. 3. The angle at which the force down the plane was equal to the force of friction (for the cabinet) was 4. Consider a very low (zero) friction, 5.0 kg skateboard on a ramp at an angle of 150 to the horizontal. What would be the net force that would cause acceleration when the skateboard is allowed to move? N What would the skateboard's acceleration down the plane? m/'s- 6 Now consider the same no-friction 3.0 kg skateboard on the same 150 ramp. If a 45kg teenager jumps on, what would be her acceleration down the ramp? m/s2 7. Imagine you are pushing a 15 kg cart full of 20 kg of bottled water up a 10" ramp. If the coefficient of friction is 0.02, what is the friction force you must overcome to push the cart up the ramp