PHYS115 Lecture Notes - Lecture 7: Net Force, Demolition Derby, Friction
27 Oct 2016
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DISCLAIMER! Only studying from this package will not fully prepare you for the midterm. I strongly
encourage you to also use the practice midterms as well as this package.
find more resources at oneclass.com
find more resources at oneclass.com
Unit 1: Vectors Kinematics
1. * Matt is on a ledge that is 80cm off the ground. He jumps and reaches a maximum height of
75cm above the ledge, and lands on the ground. What is the distance, and displacement
covered by Matt.
2. ** Matt travels 10.0m in the direction of 20° [W of N]. Then he travels 7.0m and runs 20.0m in
the direction of 30° [W of S]. Find the magnitude of the total displacement.
3. *** Matt throws two balls down from a height of 90m, 3s apart. The first ball is thrown with a
speed of 8m/s down. What is the speed of the second ball initially if it is to reach the ground a)
at the same speed as the first b) at the same time as the first
4. ** Having not skipped leg day, Matt can go from 0 to 100 real quick. In fact he can accelerate
from 0km/h to 100 km/h in 2.46s. It takes another 7.34s to reach a speed of 240km/hr.
Assuming constant acceleration A) what is the acceleration? B) How much distance does it take
to go to 240km/h? C) If the top speed is 415km/h, how long would it take to accelerate from
rest to that speed?
5. **Starting from rest, Matt moves straight up an incline of 37° at a constant acceleration for 5s
such that he reaches 23m/s. The road becomes horizontal, and Matt slows with a constant
acceleration as it follows a circular curve that changes its direction by 90° the radius of the curve
is 121m and the final speed is 7m/s. A) What is the total displacement of the trip? B) What is the
average velocity of the trip?
6. * Matt flings a marble such that it leaves the horizontal surface of the table that is 70cm high. If
marble lands with a speed of 7m/s, how fast was the marble thrown?
7. *** A bead on top of a semi sphere of radius 32cm starts sliding down from rest. By the time
the bead has moved by 30°, it has a speed of 0.92m/s. Find A) radial acceleration B) tangential
acceleration C) total acceleration
8. ** Matt is standing on a roof 14 m above the ground and drops a physics textbook. At the same
time two PHYS 115 students, one 11m from the base of the building and the other 16m from the
building, throw small stones such that all objects collide 0.9s before the beet hits the ground.
Find the speeds of the stones as they hit the book. (Assume stones are thrown from ground
level).
9. ** Matt has a catapult that throws water balloons at 35m/s and at an angle of 41° above the
horizontal. There is a flock of geese 50m down and 60m away from Matt. They are travelling at a
speed of 4m/s on the ground. If Matt takes 5s to aim, how much longer should he wait to fire
the catapult?
RELEVANT QUESTIONS: Chapter 4 – 23, 25, 27, 29, 49, 53, 67
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Only studying from this package will not fully prepare you for the midterm. I strongly encourage you to also use the practice midterms as well as this package. Unit 1: vectors kinematics: * matt is on a ledge that is 80cm off the ground. He jumps and reaches a maximum height of. 75cm above the ledge, and lands on the ground. What is the distance, and displacement covered by matt: ** matt travels 10. 0m in the direction of 20 [w of n]. Then he travels 7. 0m and runs 20. 0m in the direction of 30 [w of s]. Find the magnitude of the total displacement: *** matt throws two balls down from a height of 90m, 3s apart. The first ball is thrown with a speed of 8m/s down. In fact he can accelerate from 0km/h to 100 km/h in 2. 46s. It takes another 7. 34s to reach a speed of 240km/hr.
