Presentation on theme: "SMDEP Physics Newton’s Laws. Ch 4, #35(a): forces on stationary buckets (top, bottom) 1.34 N, 68 N 2.68 N, 68 N 3.68 N, 34 N 4.68 N, 68 N 5.Other 6.Didn’t."— Presentation transcript:
Ch 4, #41: How far up plane? How much time? 1.4.4 m, 4.4 s 2.8.8 m, 8.8 s 3.2.2 m, 2.2 s 4.Other 5.Didn’t finish
Ch 4, #47b: acceleration of system 1.Need more information 2.(m 2 g)/(m 1 +m 2 ) 3.m 2 g 4.(m 2 g)x(m 1 +m 2 ) 5.Other 6.Didn’t finish
Attendance: What’s the most pressing issue for today’s Congress? 1.Terrorism in the US. 2.Education 3.Energy 4.Natural Disaster recovery/preparation 5.Gay marriage 6.Iraq 7.Health care
New homework policy Only first and last problems are required Others are optional, “bonus points”, good practice New office hours for KR: –WTh 5:30-6:30 PM in Marigold’s
Jane is traveling in a train that moves at a constant velocity. She passes a packet of secret documents to Bill, who is standing beside the tracks. Bill catches the packet, which falls straight down into his hands. Jane… 1.Dropped the packet straight down from the window of the train 2.Threw the packet towards the front of the train 3.Threw the packet towards the back of the train
A car is moving in the +x direction at constant speed. Which of the following is true? 0 0 70 10 1.The net force on the car is in the +x direction. 2.The net force on the car is zero 3.There is a net force on the car due to gravity, in the “down” direction 4.Need more information
A car rounds a curve while maintaining a constant speed. Is there a net force on the car as it rounds the curve? 1.No. Its speed is constant. 2.Yes 3.Depends on the sharpness of the curve and the speed of the car
You are a passenger in a car and not wearing your seat belt. Without changing speed, the car makes a sharp left turn. Which of the following is correct? 1.During the turn, there is a rightward force pushing you into the door. 2.During the turn, the door exerts a leftward force on you. 3.Both of the above. 4.None of the above.
A constant force is exerted on a cart that is initially at rest on an air track. (Ignore friction). The force acts for a short time interval and gives the cart a final speed. To reach the same final speed with a force that is only half as big, the force must be exerted on the cart for a time interval: 10 0 of 70 1.Four times as long as 2.Twice as long as 3.Equal to 4.Half as long as 5.A quarter of..that for the stronger force.
A constant force is exerted on a cart that is initially at rest on an air track. (Ignore friction). The force acts for a short time interval and gives the cart a final speed. The same force is exerted for the same length of time on another cart, also initially at rest, that has twice the mass of the first one. The final speed of the heavier cart is: 10 0 of 70..that for the lighter cart. 1.One fourth 2.Four times 3.Equal to 4.Half as large as 5.double
A constant force is exerted on a cart that is initially at rest on an air track (as before). Suppose we repeat the experiment but instead of starting from rest, the cart is already moving with constant speed in the direction of the force at the moment we begin to apply the force. After we exert the same constant force for the same short time interval, the increase in the cart’s speed: 10 0 of 70 1.Is equal to twice its initial speed 2.Is equal to the square of the initial speed 3.Is equal to four times its initial speed 4.Is the same as when it started from rest 5.Cannot be determined from the info given
A car was found off the side of the road. When the police investigate, they notice cargo piled up against the passenger-side wall. What can they conclude about what happened to the car? 10 0 of 70 1.It spun off the road clockwise as viewed from above 2.It spun off the road counterclockwise as viewed from above. 3.It didn’t spin as it went off the road.