PHY-2048C – Spring 2020 SI with Camilo Exam 1 Practice Test Disclaimer: This practice test does not necessarily cover all the material that is going to appear on the test and should not be used as the sole study guide for the test. 1. Three forces act on a point: 3 N at 0°, 4 N at 90°, and 5 N at 217°. What is the net force? magnitude directi on x- component y- component first force 3 N 0° +3 N 0 N second force 4 N 90° 0 N +4 N third force 5 N 217° −4 N −3 N resultan t 1.4 N 135° −1 N +1 N 2. A ball thrown up vertically returned to the thrower after 4s. What was the velocity with which the ball was thrown? V f =V 0 +a∗t 0=V 0 +a∗t 1/ 2
Transcript
PHY-2048C – Spring 2020 SI with Camilo
Exam 1 Practice Test
Disclaimer: This practice test does not necessarily cover all the material that is going to appear on the test and should not be used as the sole study guide for the test.
1. Three forces act on a point: 3 N at 0°, 4 N at 90°, and 5 N at 217°. What is the net force?
magnitude direction x-component y-component
first force 3 N 0° +3 N 0 Nsecond force
4 N 90° 0 N +4 N
third force 5 N 217° −4 N −3 N
resultant 1.4 N 135° −1 N +1 N
2. A ball thrown up vertically returned to the thrower after 4s. What was the velocity with which the ball was thrown?
V f=V 0+a∗t
0=V 0+a∗t 1/2
V 0=−g∗t 1/2
V 0=¿ -(- 9.8)* (4/2)= 19.6 m/s
3. A motorist traveling at a constant 15m/s passes a school crossing where the speed limit is 10m/s. Just as the motorist passes the school-crossing sign, a police officer on a motorcycle stopped there starts in pursuit with constant acceleration of 3m/s^2.
a) How much time elapses before the officer passes the motorist?
b) At that time what is the officers speed?
c) At that time how far has each vehicle traveled?
4. A batter hits a baseball so that it leaves the bat at speed V 0 = 37m/s at and angle of 53.1 degrees.
a) Find the velocity (magnitude and direction) at t = 2 seconds
b) Find the time when the ball reaches its highest point and the height at this time
c) Find the horizontal distance that the ball travels as it hits the ground and the velocity right before impacting the ground.
5. A stone is thrown upward from the top of a building at an angle of 30° to the horizontal and with an initial speed of 20 m/s. The point of release is 45 m above the ground. How long does it take for the stone to hit the ground? What is the stone's speed when it hits the ground?
6. A ball is being swung by a rope in a uniform circular motion. The rope is 10 m long and the ball’s speed is a constant 20 m/s. Find the ball’s acceleration and the period.
7. A traffic light weighting 122 N hangs from a cable tied to two other cables fastened to a support. The upper cables make angles of 37∘ And 53∘ with the horizontal. These upper cables are not as strong as the vertical cable, and will break if the tension in either one of them exceed 100N. Will the traffic light remain hanging or will one of the cables break? Draw free body diagram and calculate tensions in all cables.
8. Two masses of 80 kg and 140 kg hang from a rope that runs over a pulley. You can assume that the rope is massless and inextensible, and that the pulley is frictionless. Find the upward acceleration of the smaller mass and the tension in the rope.
9. A box (containing Tim) is on a 30-degree inclined ramp. This mass is connected by a string to another mass (that contains Bob) that is suspended over a massless and frictionless pulley. Mass 1 is 10 kg; Mass 2 is 30 kg. The coefficient of kinetic friction of Mass 1 and the inclined surface is 0.2.
a) Find the acceleration of the system.
b) Find the tension in the rope.
10. A waitress shoves a ketchup bottle with mass 0.45 kg to her right along a smooth, level lunch counter. The bottle leaves her hand moving at 2.8m/s, then slows down as it slides because of a constant horizontal friction force exerted on it by the countertop. It slides for 1.0 m before coming to rest. What are the magnitude and direction of the friction force acting on the bottle?
