A car accelerates uniformly from rest and reaches a speed of 22.0 m/s in 9.00 s. If the diameter of the tire is 58.0 cm, find (a) the number of revolutions the tire makes during the motion, assuming that no slipping occurs. (b) What is the final angular speed of a tire in revolutions per second?                                          

Answer:  (54.3 rev, 12.1 rev/s) --> please show me how to get this answer!

1.The terms H II and H2 are both pronounced “H two.” What is the difference in meaning of those two terms? Can there be such a thing as H III?

2. Why do nebulae near hot stars look red? Why do dust clouds near stars usually look blue?

3. Describe the characteristics of the various kinds of interstellar gas (HII regions, neutral hydrogen clouds, ultra-hot gas clouds, and molecular clouds).

4. Describe how the 21-cm line of hydrogen is formed. Why is this line such an important tool for understanding the interstellar medium?

5. Describe the properties of the dust grains found in the space between stars.

6. Why do molecules, including H2 and more complex organic molecules, only form inside dark clouds? Why don’t they fill all interstellar space?

7. Why can’t we use visible light telescopes to study molecular clouds where stars and planets form? Why do infrared or radio telescopes work better?

8. The 21-cm line can be used not just to find out where hydrogen is located in the sky, but also to determine how fast it is moving toward or away from us. Describe how this might work.

9. Astronomers recently detected light emitted by a supernova that was originally observed in 1572, just reaching Earth now. This light was reflected off a dust cloud; astronomers call such a reflected light a “light echo” (just like reflected sound is called an echo). How would you expect the spectrum of the light echo to compare to that of the original supernova?

10. We can detect 21-cm emission from other galaxies as well as from our own Galaxy. However, 21-cm emission from our own Galaxy fills most of the sky, so we usually see both at once. How can we distinguish the extragalactic 21-cm emission from that arising in our own Galaxy? (Hint: Other galaxies are generally moving relative to the Milky Way.)

Cart 1 amd 2 are now moving toward each other when they collide and stick together. Cart 1 has a mass of 500g (.5kg) and is travelling at a speed of 0.30m/s to the right. Cart 2 has a mass of 350g (.35kg) and is travelling at a speed of 0.55m/s to the left.

A) What is their velocity (speed and direction) after the collision?

B) What % of the initial KE is lost in the collision?

Please show all work, thank you!

We assumed that the spring is ideal. In reality, as you stretch and compress the spring, frictional forces of the spring come into play. Explain how the frictional forces of the spring would or could affect your measurements.

A small loop of copper wire is inside and held perpindicular to a large, uniform magnetic field. You move the loop in circles and vary the speed. What do you observe?

As a quarterback throws the football, it leaves his hand at a height of h and at an initial speed of v0 at an angle θ above the horizontal. The receiver can’t get to the football in time and it falls onto the field. What is the ball’s speed as it hits the ground? Solve this problem in two ways: (a) using kinematics, explicitly calculating the trajectory the ball takes (b) using conservation of (kinetic + potential) energy

Explain why the sine and logarithm of 1 meter are not well-defined.

Consider an ideal massless rubber-band which has an upstretched ‘l’. A roll of 50 pennies of total mass m_pis attached to the rubber band. The new stretched length of the rubber band with the pennies hanging down from the end of the rubber band is 1:

Assume the rubber band satisfies Hookes’ law when it is stretched, what is the spring constant of the rubber band?

A small nut with mass with the mass m_nis then attached to the rubber band and both are rotated by a motor at an unknown constant frequency f. The rubber band is stretched to a length ‘l’.

Find an expression for the frequency

How long does it take for the nut to complete one rotation?

What is the angular frequency of the nut?

A small solid sphere of mass M₀, of radius R₀, and of uniform density ρ₀ is placed in a large bowl containing water. It floats and the level of the water in the dish is L. Given the information below, determine the possible effects on the water level L, (R-Rises, F-Falls, U-Unchanged), when that sphere is replaced by a new solid sphere of uniform density.

The new sphere has mass M = M₀ and radius R > R₀
The new sphere has radius R = R₀ and density ρ > ρ₀
The new sphere has radius R < R₀ and mass M = M₀
The new sphere has mass M < M₀ and density ρ = ρ₀
The new sphere has density ρ < ρ₀ and radius R > R₀
The new sphere has density ρ = ρ₀ and mass M > M₀

9.) The 17 kg shopping cart carries a 73 kg child. The shopping cart wheel base b = 480 mm and its vertical CG is symmetrically located 580 mm above the floor surface. The child remains centered symmetrically between the cart wheels with her vertical CG located 750 mm above the floor surface. Determine (a) location above the floor of the vertical CG of the cart + child in mm and (b) the tipping angle in degrees.

A transmission wire oriented parallel to the x-axis carries a current of 200 A flowing along the +x direction. A second transmission wire also oriented parallel to the x-axis but lying at a perpendicular distance of 1.30 m below the first wire carries a current of 215 A flowing along the +x direction. What is the magnitude of the total magnetic field at a point 2.3 m directly below a point midway between the two wires?

What is the direction of the net magnetic field?

transmission wire oriented parallel to the x-axis carries a current of   200 A    flowing along the +x direction. A second transmission wire also oriented parallel to the x-axis but lying at a perpendicular distance of   1.30 m    below the first wire carries a current of   215 A     flowing along the +x direction. If the location where the net magnetic field is zero is at perpendicular distance  X from the first wire, what is X ?

A transmission wire oriented parallel to the x-axis carries a current of   200 A    flowing along the +x direction. A second transmission wire also oriented parallel to the x-axis but lying at a perpendicular distance of   1.30 m     below the first wire carries a current of   215 A    flowing along the -x direction. What is the magnitude of the total magnetic field at a point   2.3 m    directly above a point midway between the two wires?

#5.Which experiment that we did do you think was the most prone to random error, and which do you think was most prone to systematic error? Why was that the case for those experiments?

Explain why lasers can be used to perform surgery and cut through metal while incandescent light cannot.

1a. What would be the effect on your calculations of specific heat of the metal if there was heat lost while transferring the metal? Explain why. 1b. What would be the effect on your calculation of specific heat of the metal if the metal you heated was wet, and contained 2% water by weight when you poured it into the calorimeter? Explain why. 1c. What would be the effect on your calculations on specific heat of the metal if you didn't wait until the final mixture reached equilibrium temperature? Explain why. 1d. What would be the effect on your calculations of specific heat of the metal if you read the temperature too high? Explain why.