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  1. M

    Kinematics Mcat Problem

    One man drops a rock from a 100 m building. At exactly the same moment, a second man throws a rock from the bottom of the building to the top of the building. At what height do the rocks meet? I have trouble understanding how there can even be an answer to this problem without more info...
  2. M

    Concept of Force Confusion

    Homework Statement Object A and B are placed on a spring. Object A has twice as much mass as object B. If the spring is depressed and released, propelling the objects into air, object A will: answer: rise to the same height as object B Homework Equations The Attempt at a...
  3. M

    MCAT Question Confusion

    A girl riding her bicycle up a steep hill decides to save energy by zigzagging rather than riding straight up. Ignoring friction, her strategy will: A. require the same amount of energy but less force on the pedals B. C. D. I missed this question and when I saw the correct answer, I couldn't...
  4. M

    MCAT Passage: Inelastic Collision

    [SOLVED] MCAT Passage: Inelastic Collision Homework Statement A car (1000 kg) and a truck (2000kg) start from rest on a long, straight track. At time t=0, the truck is at position x=0 and the car is at position x=100m. Both vehicles then accelerate toward each other and collide. Both the...
  5. M

    Simple Algerbraic Manipulation is Confusing Me

    I'm working on a chemistry problem and I'm trying to follow the derivation for % ionization (of a weak acid or base) but I can't seem to understand how rearrangement of eq. 6 results in eq. 7. In more general terms, I started with the Hendreson Hasselbalch equation: pH = pka + log(A-/AH)...
  6. M

    Mininum Work to Pull Crate

    [SOLVED] Mininum Work to Pull Crate Homework Statement A student could either pull or push, at an angle of 30 degrees from the horizontal, a 50 kilo crate on a horizontal surface, where the coefficient of kinetic friction between the crate and the surface is 0.2. The crate is to be moved a...
  7. M

    Acceleration of Block on an Apparatus

    [SOLVED] Acceleration of Block on an Apparatus Homework Statement See the attachment. Homework Equations The Attempt at a Solution I am confused about whether the tensions of the two (left and right) parts of the line are the same or not. Since the three blocks are...
  8. M

    Tension in a Line

    [SOLVED] Tension in a Line Homework Statement A rope is fixed at both ends on two trees, and a bag is hung in the middle of the rope, causing the rope to sag vertically. If the tree separation is 10 m, the mass of the bag is 5.0 kg, and the sag is 0.2 m, what is the tension in the line...
  9. M

    Angle to Drop a Package from Airplane

    Homework Statement A package is to be dropped from an airplane so that it hits the ground at a designated spot near some campers. The airplane, moving horizontally at a constant velocity of 140 km/h, approaches the spot at an altitude of .500 km above level ground. Having the designated point...
  10. M

    Distance To Center of Earthquake?

    [SOLVED] Distance To Center of Earthquake? Homework Statement An earthquake releases two types of traveling waves, called "traverse" and "longitudinal." The average speed of traverse and longitudinal seismic waves in rock are 8.9 km/s and 5.1 km/s respectively. A seismograph records the...
  11. M

    Law of reflection problem

    Homework Statement In an amusement park maze with all the walls covered with mirrors, Pilar sees Hernando's reflection from a series of three mirrors. If the reflected angle from mirror 3 is 52° for the mirror arrangement shown in the figure, in which = 12°, what is the angle of incidence on...
  12. M

    Calculate The Flux

    Homework Statement A horizontal desk surface measures 4.3 m by 2.0 m. If the Earth's magnetic field has magnitude 0.32 mT and is directed 45° below the horizontal, what is the magnetic flux through the desk surface? Homework Equations Flux = B*A*Cos(a) Where A is the area, B is the...
  13. M

    Calculate Free Energy for Formation

    I realize that this is a chem prob, but I'm stuck with what I thought was a straightforward problem while studying for my physical chemistry exam. Homework Statement The standard molar enthalpy of combustion of solid phenol (C6H5OH) is -3054 kJ/mol at 298k and it's standard molar entropy...
  14. M

    What's the Current of the Potential Difference?

    Homework Statement A potential difference is applied between the electrodes in a gas discharge tube. In 2.0 s, 3.3*10^16 electrons and 1.2*10^16 singly charged positive ions move in opposite directions through a surface perpendicular to the length of the tube. What is the current in the tube...
  15. M

    Width of Slicon Strip?

    Homework Statement A strip of doped silicon 270 µm wide contains 9.1E22 conduction electrons per cubic meter and an insignificant number of holes. When the strip carries a current of 110 µA, the drift speed of the electrons is 44 cm/s. What is the thickness of the strip? Homework...
  16. M

    Potential difference between Bird's Feet?

    Homework Statement A bird sits on a high-voltage power line with its feet 2.0 cm apart. The wire is made from aluminum, is 3.0 cm in diameter, and carries a current of 160 A. What is the potential difference between the bird's feet? Homework Equations I=neAv Where I is current, n is...
  17. M

    Charge on Parallel Plate Capacitor

    I am having a really tough time providing an argument for myself over why the answer is true: The question: A parallel plate capacitor is attached to a battery that supplies a constant potential difference. While the battery is still attached, the parallel plates are separated a little...
  18. M

    What is the Potential difference?

    Homework Statement As a positron moves through a region of space, its speed decreases from 9.20*10^6 m/s to 2.20*10^6 m/s. The electric force is the only force acting on the positron. Homework Equations KE1 + U1 = KE2 + U2 Where KE is kinetic energy and U is potential energy. The Attempt...
  19. M

    Spring Constant Due to 2 Charges

    Homework Statement A tiny sphere with a charge of q = +6.1 µC is attached to a spring. Two other tiny charged spheres, each with a charge of -4.0 µC, are placed in the positions shown in the figure, in which b = 3.6 cm. The spring stretches 5.0 cm from its previous equilibrium position...
  20. M

    Where is the Electric Field Equal to Zero?

    Homework Statement Two tiny objects with equal charge of 85.0 µC are placed at two corners of a square with sides of 0.295 m, as shown. How far above and to the left of the corner of the square labeled A would you place a third small object with the same charge so that the electric field is...
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