Download Chapter 1 Quick Review

TA: Tomoyuki Nakayama
February 1st – February 2nd, 2010
PHY 2048: Physics 1 with Calculus, Spring 2010
Review: Chapter 5.1- 6.5
The purpose of this review is to refresh your memory. Physics is a cumulative subject, so make it
sure that you understand basic concepts and typical problem solving techniques in previous chapters
before moving on to a new chapter.
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A. Application of Newton’s Laws
1. Two forces are exerted on a block of mass m. One of the forces F1 is along +x direction. The block
accelerates in the +y direction.
a) Without any calculation, find which quadrant the 2nd force is in.
b) Express F2 in unit-vector notation.
2. A block with mass m is sliding down a frictionless slope of θ. Find the acceleration of the block
and the normal force exerted on the block.
3. Two blocks are connected by a string with a negligible mass. The surface is frictionless.
a) Choose a coordinate system for each block so that you can
express the accelerations of two blocks as a common acceleration.
b) What are the acceleration and the tension?
B. Friction
1. A horizontal force F = 100 N is applied to a 5-kg crate on a 30º slope.
The crate is initially at rest. Find the acceleration of the crate. μs = 0.4 μk =
0.2
C. Uniform Circular Motion
1. A Ferris wheel of radius 10 m is rotating at a constant speed of 5 m/s. Find the force exerted on a
50-kg rider by the seat a) at the top of the motion, b) at the bottom and c) halfway between the top
and bottom.
2. A car is traveling at a constant speed around a frictionless banked
circular track of radius R. The bank angle is θ. What is the speed of
the car?
TA: Tomoyuki Nakayama
February 1st – February 2nd, 2010
PHY 2048: Physics 1 with Calculus, Spring 2010
Practice Exam Problems (Chapter 5.1- 6.5)
Working on this problem set is optional, but it is strongly recommended. It is highly likely that some
of these problems will appear in the exams. Do it on a weekly basis. Cramming is tiring and
sometimes it ends up in a disaster.
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1. Equal forces F act on isolated bodies A and B. The mass of B is three times that of A. The
magnitude of the acceleration of A is: (Newton’s 2nd Law) a. three times that of B b. 1/3 that of B
c. the same as B d. nine times that of B e. 1/9 that of B
2. Two blocks (A and B) are in contact on a horizontal
frictionless surface. A 36-N constant force is applied to A as
shown. The magnitude of the force of A on B is: (Contact
Force) a. 1.5 N b. 6.0 N c. 29 N d. 30 N e. 36 N
3. A 1-N pendulum bob is held at an angle θ from the vertical by a 2-N
horizontal force F as shown. The tension in the string supporting the
pendulum bob (in newtons) is: (Tension) a. cosθ b. 2/cosθ c. √5 d.
1 e. non of the above
4. A 90-kg man stands in an elevator that has a downward acceleration of
1.4 m/s2. The force exerted by him on the floor is about: (Normal Force) a. zero b. 90 N c. 760
N d. 880 N e. 1010 N
5. Block A, with mass mA is initially at rest on a frictionless horizontal floor. Block B, with mass mB
is initially at rest on the horizontal top surface of A. The coefficient of static friction between the two
blocks is μs. Block A is pulled with a horizontal force. Block B begins to slide with respect to block
A if the force is greater than: (Maximum Static Friction) a. mAg b. mBg c. μsmAg d. μsmBg
e. μs(mA+mB)g
6. Block A, with a mass of 10 kg, rests on a 30 incline. The coefficient
of static friction is 0.3 and the coefficient of kinetic friction is 0.20.
The attached string is parallel to the incline and passes over a massless,
frictionless pulley at the top. Block B, with a mass of 8.0 kg, is
attached to the dangling end of the string. The acceleration of A is
(Kinetic Friction) a. 0.69 m/s2, up the plane b. 0.69 m/s2,down the
plane c. 2.6 m/s2, up the plane d. 2.6 m/s2, down the plane e. 0
7. A 0.2-kg stone is attached to a string and swung in a circle of radius 0.6 m on a horizontal and
frictionless surface. If the stone makes 150 revolutions per minute, the tension force of the string on
the stone is: (Centripetal Force) a. 0.03 N b. 0.2 N c. 0.9 N d. 1.96 N e. 30 N
8. An automobile moves on a level horizontal road in a circle of radius 30 m. The coefficient of
friction between tires and road is 0.50. The maximum speed with witch this car can round this curve
is: (Circular Motion due to Friction) a. 3.0 m/s b. 4.9 m/s c. 9.8 m/s d. 12 m/s e. 13 m/s
Answers: 1-a 2-d
3-c 4-c 5-e 6-a 7-e 8-d