1 PHY131H1F - Class 6 • 4.5 Solving Force Problems • 4.6 Newton’s Third Law • The Normal Force • Hooke’s Law A truck is pushing a car up an incline with a constant forward acceleration . The incline has an angle with respect to the horizontal. Note: the car and the truck remain in contact during this acceleration. Which is larger, the magnitude of the force the truck applies on the car or the magnitude of the force the car applies on the truck? A. The magnitude of the force the truck applies to the car. B. The magnitude of the force the car applies to the truck. C. The magnitude of the two forces are the same. D. We must know the angle to answer this question. E. We must know the masses of the truck and the car to answer this question.
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PHY131H1F - Class 6 - U of T Physicsjharlow/teaching/phy131f15/lec06... · PHY131H1F - Class 6 ... Class 6 Preclass Quiz on MasteringPhysics This was due this morning at 8:00am ...
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PHY131H1F - Class 6
• 4.5 Solving Force Problems
• 4.6 Newton’s Third Law
• The Normal Force
• Hooke’s Law
A truck is pushing a car up an incline with a constant forward
acceleration 𝑎. The incline has an angle with respect to the
horizontal. Note: the car and the truck remain in contact during
this acceleration. Which is larger, the magnitude of the force
the truck applies on the car or the magnitude of the force the
car applies on the truck?
A. The magnitude of the force the truck applies to the car.
B. The magnitude of the force the car applies to the truck.
C. The magnitude of the two forces are the same.
D. We must know the angle to answer this question.
E. We must know the masses of the truck and the car to
answer this question.
𝑎
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Class 6 Preclass Quiz on MasteringPhysics
This was due this morning at 8:00am
47% of students answered correctly: “An object is at rest
on a tabletop. Earth pulls downward on this object with a
force equal in magnitude to mg. If this force serves as the
action force, what is the reaction force in the action–
reaction pair?” The object pulling upward on the Earth.
90% of students answered correctly A large truck collides
head-on with a small car. The car is severely damaged as
a result of the collision. According to Newton's third law,
The force on the truck is equal to the force on the car.
96% of students answered correctly A spring stretches by
21.0 cm when a 135 N object is attached. What is the
weight of a fish that would stretch the spring by 57.8 cm?
Answer = 371 N. [Use F2 = F1 (x2/x1) ]
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Class 6 Preclass Quiz Student Comments
“Should the pair of action force and reaction force be on
the two same things and be attached with each other?”
Harlow note: the 2 forces of an action-reaction-pair
always act on different objects! If it is a long range
force, then these objects need not be connected.
“Will the k of a spring change?”
Harlow note: No. For an ideal spring (which is all the
springs in this course) k is a constant for a particular
spring (unless you cut it in half or something!)
"If you're in free fall, then Earth's gravity causes you to