Classical Mechanics Answers

Ultrasound bioeffects mainly depend on

[multiple answers]:

A. Wavelength of ultrasound

B. Intensity of irradiation

C. Time of irradiation

D. Velocity of ultrasound

Axial resolution of diagnostic ultrasound can

be improved by [multiple answers]

A. damping

B. pulsing

C. focusing

D. increasing operating frequency

What is the wavelength of a 5MHz

ultrasound pulse in soft tissue?

Assume that the speed of ultrasound

in soft tissue is 1500m/s. [Best

answerl

A. 0.3 mm

B. 0.5 mm

C. 3 mm

D. 5 mm

In which of the following materials

is the speed of ultrasound greatest

[Best answer]

A. Air

B. Bone

C. Water

D. Soft tissue

An ultrasound beam passing through the body

[multiple answers]

A. is attenuated

B. produces heating of tissues

C. can be reflected

D. produces ionization

Which of these statements is (are) true?

1. An object can have zero acceleration and be at rest.

2. An object can have nonzero acceleration and be at rest.

3. An object can have zero acceleration and be in motion.

a) 1 only b) 1 and 3 c) 1 and 2 d) 1, 2, and 3

1. A 3-m-diameter, 7-m-long cylindrical tank is completely filled with water. The tank is pulled by a truck on a level road with the 7-m-long axis being horizontal. Determine the pressure difference between the front and back ends of the tank along a horizontal line when the truck (a) accelerates at 3 m/s² and (b) decelerates at 4 m/s².

2. A 30-cm-diameter, the 90-cm-high vertical cylindrical container is partially filled with 60-cm-high water. Now the cylinder is rotated at a constant angular speed of 180 rpm. Determine how much the liquid level at the center of the cylinder will drop as a result of this rotational motion.

3. A 4-m-diameter vertical cylindrical milk tank rotates at a constant rate of 15 rpm. If the pressure at the center of the bottom surface is 130 kPa, determine the pressure at the edge of the bottom surface of the tank. Take the density of the milk to be 1030 kg/m³.

1. A water tank is being towed by a truck on a level road, and the angle the free surface makes with the horizontal is measured to be 8 degrees. Determine the acceleration of the truck.

2. Consider two water tanks filled with water. The first tank is 8 m high and is stationary, while the second tank is 2 m high and is moving upward with an acceleration of 5 m/s². Which tank will have a higher pressure at the bottom?

3. A water tank is being towed on an uphill road that makes 14° with the horizontal with a constant acceleration of 3.5 m/s² in the direction of motion. Determine the angle the free surface of the water makes with the horizontal. What would your answer be if the direction of motion were downward on the same road with the same acceleration?

1. A 200-kg granite rock (p = 2700 kg/m³) is dropped into a lake. A man dives in and tries to lift the rock. Determine how much force the man needs to apply to lift it from the bottom of the lake. Do you think he can do it?

2. The hull of a boat has a volume of 180 m³, and the total mass of the boat when empty is 8560 kg. Determine how much load this boat can carry without sinking (a) in a lake and (b) in seawater with a specific gravity of 1.03.

3. It is estimated that 90 percent of an iceberg’s volume is below the surface, while only 10 percent is visible above the surface. For seawater with a density of 1025 kg/m³, estimate the density of the iceberg.

4. The weight of a body is usually measured by disregarding buoyancy force applied by the air. Consider a 20-cm-diameter spherical body of density 7800 kg/m³. What is the percentage error associated with the neglecting of air buoyancy?

1. The cart is allowed to roll freely down the inclined plane due to its weight. Show that the slope of the surface of the liquid, theta. during the motion is theta = phi.

2. The cart is given a constant acceleration a up the inclined plane. Show that the lines of constant pressure within the liquid have a slope of tan theta = (a cos phi)/ (a sin phi + g).

3. A large container of benzene is transported on the truck. Determine the level in each of the vent tubes A and B if the truck accelerates at a = 1.5 m/s². When the truck is at rest, h_A = h_B = 0.4 m.

4. A woman stands on a horizontal platform that is rotating at a constant angular velocity w. If she is holding a cup of tea, and the center of the cup is 0.9 m from the axis of rotation, determine w if the slope angle of the liquid's surface is 5°. Neglect the size of the cup.