Download Physics 11 Assignment #2

Physics 11 Assignment #2
Dynamics
Physicist:
Learning Outcomes (Student will be able to…):



apply Newton's laws of motion to explain inertia and the relationships among force, mass, and acceleration
analyze natural and technological systems to interpret and explain their structure and dynamics
use vectors to represent forces
□ (1) Does not meet
□ (2) Meet outcome with
outcome
assistance
□ (3) Meets outcome
□ (4) Meets outcome
with minimal or no
assistance
with in-depth
understanding
Level 1 – Knowledge/Comprehension (4 points)
1. Define net force.
2. Define static frictional force.
3. Multiple Choice: Shade in the most appropriate answer.
An airplane is moving at constant velocity in a straight level flight. What is the
net force acting on the plane?
a. zero
b. upward
c. downward
d. in the direction of motion
A cable on an elevator exerts a 6 N upward force. The downward force of
gravity on the elevator is 4 N. The elevator could be
a. moving upward with constant speed.
b. downward with a constant speed.
c. moving upward with decreasing speed.
d. moving upward with increasing speed.
a
b
c
d
a
b
c
d
Level 2 – Application/Analysis (12 points)
4. A hockey stick exerts a force of 575 N[E] on a 0.125-kg hockey puck. What is the acceleration of
the puck? Show a free-body diagram and relevant equations. (3)
5. You are moving a 95 kg wood crate across a wood floor (the coefficient of static friction is 0.40).
What is the magnitude of the force with which you must push to start the crate moving? Show a freebody diagram and relevant equations. (3)
6. Two objects, m1 and m2, are accelerated independently by forces of equal magnitude. Object m1
accelerates at 10.0 m/s2 and m2 at 20.0m/s2. What is the ratio of (a) their inertial masses? (b) their
gravitational masses? (3)
7. A car can accelerate from rest to 100 km/h (or 27.8 m/s) in 6.0 s. If its mass is 1500 kg, what is
the magnitude of the applied force? Show a free-body diagram and relevant equations. (3)
Level 3 – Synthesis/Evaluation (4 points)
m1
m2
8. An Atwood machine consists of two masses (m1=3.8 kg) and (m2=4.2 kg). What is the
acceleration of the masses? What is the tension in the rope? Note: you must derive the equation for
tension using a free-body diagram to receive full credit. (2)
9. A cardboard box of negligible mass filled with 45 kg of paper sits on a ramp that makes an angle
of 21o with the horizontal. The coefficient of static friction is 0.42. Will the box slide down the ramp?
Explain with an appropriate problem-solving method. (2)