A lens of focal length f₁ = +20 cm has an object positioned 50 cm in front of it. A second lens of focal length f₂= -15 cm is located 10 cm behind the first lens. a) Determine the two image positions for this combination of lenses. b) Is each image real or virtual, upright or inverted, and magnified or demagnified?

A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 77 kg, and the height of the water slide is 12.9 m. If the kinetic frictional force does -7.1 × 103 J of work, how fast is the student going at the bottom of the slide?

Select TWO analytical tool that uses electromagnetic waves to measure velocity. Explain how each tool uses electromagnetic waves to measure velocity. Describe the region of the electromagnetic spectrum that the tools you selected use. What properties distinguish each of these two regions of the spectrum from other regions?

The all-new iPhone Xs has a 2716mAh Li-ion battery. After a full charge, Sam used it for exactly a full day without recharging, leaving 15% battery in the phone. If the voltage of the battery is 3.8V, estimate (1) the average electric current (in Amperes), (2) the total amount of electric energy (in Joules), and (3) the average power (in Watts) that Sam’s iPhone Xs consumed during that day. This battery only has a mass of about 50 grams. As a comparison, search online and then estimate the amount of energy released by the explosion of 50 grams of TNT

In the figure here, a stationary block explodes into two pieces L and R that slide across a frictionless floor and then into regions with friction, where they stop. Piece L, with a mass of 2.5 kg, encounters a coefficient of kinetic friction μL = 0.43 and slides to a stop in distance dL = 0.38 m. Piece R encounters a coefficient of kinetic friction μR = 0.45 and slides to a stop in distance dR = 0.40 m. What was the mass of the block?

A hot-air balloon is drifting in level flight due east at 2.9 m/s due to a light wind. The pilot suddenly notices that the balloon must gain 26 m of altitude in order to clear the top of a hill 120 m to the east.

GIVENS:

How much time does the pilot have to make the altitude change without crashing into the hill? = 41s

What minimum, constant, upward acceleration is needed in order to clear the hill? = 3.0*10^-2m/s^2

What is the horizontal component of the balloon’s velocity at the instant that it clears the top of the hill? = 2.9m/s

You are pushing a box (m = 4 kg) horizontally with a constant force F = 30 N. After pushing it for a distance d = 5 m, the box reaches a hill inclined at θ = 25°. You stop pushing the box as soon as it reaches the hill. The coefficient of kinetic friction between the box and the road is µk = 0.4 and the hill is frictionless. How far up the hill is the box going to go?

Question #10: What is the basic character for RC circuit? In other words, how do the current and voltage change with time? What about the discharging? What is the time constant? How to compute it? How to compute the time constant. How does the charge capacitor change with respect to time?

I can't understand the difference between 'the work the electric force does' and 'the work the electric field does'. Could you explain it in detail?

Two phenomena for waves you have seen this week are interference, specifically spatial, and resonance.

For each phenomenon, describe briefly what is happening and why, then considering that each one can be good or bad depending on the situation, see if you can give two cases for each - 2 where good, 2 where not good.

Please no handwritten or picture responses - only typed replies.

In proton beam therapy, a beam of high-energy protons is used to kill cancerous cells in a tumor. In one system, the beam, which consists of protons with an energy of 2.8×10−11J, has a current of 72 nA. The protons in the beam mostly come to rest within the tumor. The radiologist has ordered a total dose corresponding to 3.8×10−3J of energy to be deposited in the tumor.

Part A How many protons strike the tumor each second? Express your answer as a number of protons.

Part B: How long should the beam be on in order to deliver the required dose?

A see-saw made from 4 meter board sits on a pivot at its center. A child weighing 280 N sits 1.75 m away from the center. A second child who weighs 330 N sits on the other side such that the board remains horizontal and steady. (a) What is the torque about the pivot point due to the weight of the first child? (b) how far from the center does the second child sit? (c) What is the force (magnitude and direction) that the pivot applies to the board? Now you come and push on the end of the seesaw nearest the second child with a force of 110 N. You don’t push straight up, but at an angle of 25° from the vertical – tilted toward the center of the seesaw. The first child moves to maintain equilibrium. (d) Based on your intuition, which way should the child move? Towards or away from the center? (e) Calculate how far she is now from the center? (f) What is the force now (magnitude and direction) that the pivot applies to the board?

***Please help me with solving (e) and (f) with the equations so that I can learn how to do it. Thanks***

(1) The earth's radius is 6.37×106m; it rotates once every 24 hours.

(A) What is the speed of a point on the equator?

(2) The (Figure 1) shows two thin beams joined at right angles. The vertical beam is 13.0 kg and 1.00 m long and the horizontal beam is 28.0 kg and 2.00 m long. Neglect the lateral dimensions of the beams.

(A) Calculate the gravitational torque on the joined beams about an axis through the corner.

(3) A bowling ball is far from uniform. Lightweight bowling balls are made of a relatively low-density core surrounded by a thin shell with much higher density. A 7.0 lb (3.2 kg) bowling ball has a diameter of 0.216 m; 0.196 m of this is a 1.6 kg core, surrounded by a 1.6 kgshell. This composition gives the ball a higher moment of inertia than it would have if it were made of a uniform material. Given the importance of the angular motion of the ball as it moves down the alley, this has real consequences for the game.

(A) Compare the moments of inertia for these models by finding the ratio of Ir and Iu.

Moderating a Neutron In a nuclear reactor, neutrons released by nuclear fission must be slowed down before they can trigger additional reactions in other nuclei. To see what sort of material is most effective in slowing (or moderating) a neutron, calculate the ratio of a neutron's final kinetic energy to its initial kinetic energy, Kf/Ki, for a head-on elastic collision with each of the following stationary target particles. (Note: The mass of a neutron is m=1.009u, where the atomic mass unit, u, is defined as follows: 1u=1.66×10−27kg.) 1. An electron (M=5.49×10−4u). Express your answer using four significant figures. 2. A proton (M=1.007u). Express your answer using one significant figure. 3. The nucleus of a lead atom (M=207.2u). Express your answer using four significant figures.

Part A

Find the kinetic energy of a 1.84×10³ kg satellite in a circular orbit about the Earth, given that the radius of the orbit is 1.46×10⁴ miles.

Part B

How much energy is required to move this satellite to a circular orbit with a radius of 2.72×10⁴ miles?