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# Review%20Set-2-F2012.pdf

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McMaster University

Physics

PHYSICS 1L03

Reza Nejat

Fall

Description

Review Set 2 Phys 1L03
Questions for REVIEW
1. What is 7.01 × 3.1415 with the correct number of significant figures?
Ans: 22.0
2. Two different forces, acting on the same object, are measured. One force is 2.0031 N and the other
force, in the same direction, is 3.12 N. These are the only forces acting on the object. Find the total
force on the object using the correct number of significant figures.
Ans: 5.12 N
3. A car slows down with constant acceleration from a speed of 111.6 km/h to 43.20 km/h over a
distance of 380.0 m. How long does it take?
Ans: 17.67 s
4. A large ice block of mass M = 80 kg is held stationary on a frictionless ramp. The ramp is at an
angle 0f ▯ = 36.87 oabove horizontal. If the ice block is held in place by a tangential force along
the surface of 2he ramp (at the angle ▯ above horizontal), the magnitude of force is:
Ans: 4.70 ▯ 10 N (F = mg sin ▯)
5. A large ice block of mass M = 80 kg is held stationary on a frictionless ramp. The ramp is at an
angle 0f ▯ = 36.87 above horizontal. If the ice block is held in place by a horizontal force,
directed horizontally toward the center of the ice block, the magnitude of force is:
Ans: 5.88 ▯ 10 2 N (F = mg sin ▯/cos ▯)
6. A large ice block of mass M = 80 kg is held stationary on a rough ramp. The ramp is at an angle
o
0f ▯ = 36.87 above horizontal, and has a coefficient of kinetic friction between the block and the
ramp ▯ = 0.1 . If the ice block is held in place by a tangential force along the surface of the ramp
(at the angle ▯ above horizontal), the magnitude of force is:
Ans: 4.07 ▯ 10 2 N (F = mg sin ▯ -▯ mg cos ▯)
7. A large block of mass M = 80 kg is held stationary on a frictionless ramp. The ramp is at an angle
0f ▯ = 36.87 above horizontal, and has a coefficient of kinetic friction between the block and the
ramp ▯ = 0.1. If the block is held in place by a horizontal force, directed horizontally toward the
center of the ice block, the magnitude of force is:
2
Ans: 4.74 ▯ 10 N (F = [mg (sin ▯ -▯ cos ▯) /(cos ▯ + -▯ sin ▯)])
8. The displacement from the equilibrium caused by a wave on a string is given by: y(x, t) = (-
0.00200 m) sin [40 m -1)x – (800 s )t]. What are the number of waves in 1 m ,
Ans: 6.4
9. What is the frequency of the above wave:
Ans: 127 Hz
10.What is the speed of the above wave:
Ans: 20.0 m/s
11.In your High School State Championship football game the intensity level of the shout of a single
person in the stand at the center of the field is about 50 dB. What would be the intensity level if all
10,000 family and friends of your school shout roughly from the same distance?
Ans: 90 dB 12.A standing wave in a column of air with one end open and another one closed has a frequency of
390 Hz. The next higher harmonic has a frequency of 650 Hz. Determine the fundamental
frequency.
Ans: 130 Hz
13.How long is the column of air of pervious problem? Speed of sound = 340 m/s
Ans: 0.65 m
14.Two uniform spheres, A and B, with equal density (mass per volume) are in contact with one
another. The mass and volume of sphere A is five times those of sphere B. The center of mass of
the system, of two sphere A and B, is
a. at the point where A and B touch
b. inside sphere B somewhere on the line joining the centers of A and B.
c. inside sphere A somewhere on the line joining the centers of A and B. *
d. at the center of A.
e. outside of both spheres.
Ans: c
15. An iron man is lifted by a lift that has a magnetic hook. Which one
of the following free body diagrams best represents forces on the
iron man? T is the tension of the cable and W is the weight of iron
man, M is the magnetic force and N is the normal force.
Ans:
16.A heavy box is resting on the floor and you would like to push the box to tip it over on its
side, using the minimum force possible. Which of the force vectors in the diagram shows
the correct location and direction of the force? The forces have equal horizontal
components. Assume that there is enough friction so the box does not slide; instead it
rotates around point P.
Ans: b 17.A picture hangs on the wall suspended by two strings, as shown. The
tension in left string is 1.7 N. The tension in right string is:
Ans: Less than 0.85 N
18.A dumbbell, as shown, has a connecting bar of
negligible mass. If m 1 5.0 kg and m =210 kg, and
are separated by 0.70 m, find the location of center of
mass of the dumbbell from m (t1e left mass), from
m2 (the right mass), and from the middle point betwe

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