Question 1

A hockey puck slides across a frictionless ice surface at constant velocity. Which of the following statements is correct?

Accepted Answer

The net force on the puck is zero.

Question 2

An astronaut has a mass of 80 kg on Earth. She travels to the Moon, where gravitational acceleration is about $$\frac{1}{6}$$ that of Earth. Which of the following correctly describes her mass and weight on the Moon?

Accepted Answer

Her mass is the same, but her weight is less.

Question 3

A child sits on a rotating merry-go-round. She moves from the edge toward the center. What happens to her tangential speed and her angular velocity?

Accepted Answer

Her tangential speed stays the same; her angular velocity increases.

Question 4

Which of the following quantities is measured in radians per second squared ($$\mathrm{$$rad/s^2$$}$$)?

Accepted Answer

Angular acceleration

Question 5

A spinning top completes one full revolution every $$0.200$$ seconds. What is its angular frequency in radians per second?

Accepted Answer

$$31.4\ \mathrm{rad/s}$$

Question 6

A uniform ladder leans against a smooth wall with its base on the ground. The system is in static equilibrium. Which set of conditions must be satisfied?

Accepted Answer

Both the net force and the net torque must be zero.

Question 7

Two cylinders are made of different materials but have exactly the same mass. Cylinder A is solid; Cylinder B is hollow with the same outer radius. When you try to spin them about their central axis, which requires more torque to reach the same angular acceleration?

Accepted Answer

Cylinder B, because its mass is distributed farther from the axis.

Question 8

A 15.0 kg box is pushed along a warehouse floor and released with an initial speed of $$3.50\ \mathrm{m/s}. A $$constant friction force of $$18.0\ \mathrm{N}$$ acts on the box. How far does the box travel before coming to rest? (Use the work-energy theorem.)

Accepted Answer

$$7.08\ \mathrm{m}$$

Question 9

A probe is sent to a distant moon with mass $$m_{moon} = 7.35 	imes 10$$^{22}$$\ \mathrm{kg}$$ and radius $$r_{moon} = 1.74 	imes 10$$^{6}$$\ \mathrm{m}. If a $$rock on Earth weighs $$49.0\ \mathrm{N}$$, what does it weigh on the surface of this moon?

Accepted Answer

$$2.00\ \mathrm{N}$$

Question 10

A mechanic must tighten a bolt to a torque of $$85.0\ \mathrm{N \cdot m}. $$She uses a wrench that is $$45.0\ \mathrm{cm}$$ long. Because of the tight space, she can only pull at an angle of $$55.0^\circ$$ with respect to the wrench handle. With what magnitude of force must she pull?

Accepted Answer

$$237\ \mathrm{N}$$

Question 11

A motorcycle rounds a flat, unbanked curve of radius $$60.0\ \mathrm{m}. $$The coefficient of static friction between the tires and the road is $$0.70. $$What is the maximum speed at which the motorcycle can safely navigate the curve without sliding? ($$g = 9.80\ \mathrm{m/s^2$})$$

Accepted Answer

$$20.4\ \mathrm{m/s}$$

Question 12

A uniform $$3.0\ \mathrm{m}$$ long plank of mass $$20.0\ \mathrm{kg} is $$supported at each end by a scale. A $$70.0\ \mathrm{kg}$$ student stands $$1.0\ \mathrm{m}$$ from the left end. What does each scale read in Newtons?

Accepted Answer

Left: $$343\ \mathrm{N}$$, Right: $$255\ \mathrm{N}$$

Question 13

A student holds a $$40.0\ \mathrm{N}$$ textbook in their hand with their arm extended horizontally. The hand is $$35.0\ \mathrm{cm}$$ from the elbow (pivot). The biceps muscle attaches $$4.0\ \mathrm{cm}$$ from the elbow. What upward force must the biceps exert to hold the book stationary? (Ignore the weight of the forearm.)

Accepted Answer

Question 14

A solid cylinder and a hollow cylinder, each with mass $$M$$ and radius $$R$$, are released from rest at the top of an incline. Which will reach the bottom first, and why?

Accepted Answer

The solid cylinder, because it has a smaller moment of inertia.

Question 15

A car of mass $$1200\ \mathrm{kg} is $$traveling around a curve of radius $$50.0\ \mathrm{m} at a $$speed of $$15.0\ \mathrm{m/s}. $$What is the minimum coefficient of static friction required to prevent the car from skidding?

Accepted Answer

$$0.46$$

Question 16

A $$2.0\ \mathrm{kg}$$ mass is attached to a string and swung in a horizontal circle of radius $$1.5\ \mathrm{m} at a $$constant speed of $$4.0\ \mathrm{m/s}. $$What is the tension in the string?

Accepted Answer

$$21.3\ \mathrm{N}$$

Question 17

A uniform beam of length $$6.0\ \mathrm{m}$$ and mass $$30.0\ \mathrm{kg} is $$supported horizontally at its ends. A $$60.0\ \mathrm{kg}$$ person stands $$1.0\ \mathrm{m}$$ from the left end. What is the force on the right support?

Accepted Answer

$$245\ \mathrm{N}$$

Question 18

A flywheel with moment of inertia $$I = 2.0\ \mathrm{kg \cdot m^2$} is $$spinning at $$10.0\ \mathrm{rad/s}. $$How much work must be done to bring it to rest?

Accepted Answer

$$100\ \mathrm{J}$$

Physics 2010 Practice Exam 2 – Step-by-Step Study Guidance

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