Q- A student is trying to decide what to wear. His bedroom is at 20.0 degrees Celsius. His skin temperature is 35.0 degrees Celsius. The area of his exposed skin is 1.50 m^{2}. People all over the world have skin that is dark in the infrared, with emissivity about 0.900. Find the net energy loss from h…

## . September 2018

### Heat Radiation

### Sound: Intensity and Loudness

Q- When a pin of mass 0.120 g is dropped from a height of 0.80 m and 0.05% of its energy is converted into a sound pulse with a duration of 0.1 s.

(a) Estimate the range at which the dropped pin can be heard if the minimum audible intensity is 10^{-11} W/m^{2}.

(b) Your result in (a) is much too larg…

### Collision

Q- A truck was traveling north when, at intersection, collided with a car traveling east. The two vehicles remained joined together after the collision. The skid marks leading from the intersection 20 m at an angle of 30^{o} north of east before stopping. The truck weighed 1200 kg and the car weighed …

### Rotational Oscillations

Q- Two disks with moments of inertia I_{1} (top disk) and I_{2} (bottom disk) are connected by a mass-less torsion spring which produces a restoring torque with magnitude |τ| = c |θ_{1}-θ_{2}| on each disk, where θ_{1} and θ_{2} are the angular positions of the disks. (You can imagine that this system is free…

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