Physics Answers

A particle is displaced 60 cm to the north and then is given a second displacement of 90 cm directly to the east. What is the average velocity of the particle if it covers the entire displacement within 2.15 seconds?

0.085 m3 of air are compressed isentropically from 1937 kPa and -4 oC to 5873 kPa . Find (a) t2 in oC and V2, (b) Wnf, and © H and U.

An inclined plane makes an angle of with the horizontal. Find the constant force, applied parallel to the plane, required to cause a box to slide (a) up the plane with acceleration 1.2 m/s² and (b) down the incline with acceleration 1.2 m/s². Neglect friction forces.

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

A 12-kg box is released from the top of an incline that is 5.0m long and makes an angle of 40° to the horizontal. A 60-N friction force impedes the motion of the box. (a) What will be the acceleration of the box? (b) How long will it take to reach the bottom of the incline?

A simple pendulum is found to vibrate 50 times within 200s. When 1.5m of its length is reduced to a certain length, it vibrates 50 times in 175s. Find the original length of the pendulum.