kinetic energy

  1. P

    I Estimating the damage to a material based on force or kinetic energy

    I'm programming a game in which I'd like to simulate the real world physics of an attack using primarily medieval style weapons. Think dwarf fortress, but rather than assigning damage numbers we're calculating force or kinetic energy. Getting that much is easy enough since I can find the mass of...
  2. L

    Man jumping onto a see-saw to launch bricks vertically

    I drew a diagram for the a) part The person is h meters high So GPE= 100 x 9.8x h GPE= 980h j KE = 980h when the person hits the see saw KE=1/2mv² 980h=0.5 x 5 x v² Now it v²=u²+2as For the brick going up to 10m v = 0 u=? a=-9.8ms-² s=10m u²=2 x 9.8 x 10 u=14m/s We can assume that u=14m/s is...
  3. srecarey

    Diatomic Molecules

  4. lilymay992

    Kinetic Energy of Protons

    So first I tried to use KE=1/2 x m x v^2 but then realised I didn’t have the velocity and I can’t figure out a way to obtain it. I then tried to work out the energy using a different equation, W= q x v but that left me with 1.28x10^-14 J which seemed too small. I also then have to calculate the...
  5. O

    B Confused by the relationship of work and kinetic energy

    So the equation for work is W = F * s F = m * a, so W = m * a * s Transferring this to units of measurement gives us: J = kg * m * s-2 * m Or simplified: J = kg * m2 * s-2 Transferring back to units of quantity: W = m * v2 How can that be correct? Obviously Ekin = 1/2 * m * v2. Where did that...
  6. N

    How would we increase the rotation rate of very large structures in deep space?

    Imagine a 400-meter-long pipe with a 1600-meter diameter, floating in inter-planetary space. It is spinning at 0.5 gravity along its major axis and there are no secondary-axes spins. We need to increase rotation to 0.85 g. Its density is a uniform 2.3 kg/m³ and it weighs 49,120,056 kg. Thanks to...
  7. M

    Force on a pin from a pendulum and a string

    1. Determine the velocity of the ball when it is 30degrees from the horizontal: U1 = mgh = mg(0.8m) U2 = mgh = mg(0.4+0.4cos(30)) = mg(.74641) ΔU = U2 - U1 = mg(.74641 - .8) = mg(-0.051433) T1 =0 T2 = 0.5mv^2 ΔT = T2 - T1 = 0.5mv^2 ΔU = ΔT mg(-0.051433) = 0.5mv^2 ====> v = 1.025394 2. Use...
  8. D

    How to find the energy of an object that was at rest?

    1. Homework Statement In two rockets, one of which moves and the other is at rest, the motors are connected for a short time. During their operation they throw the same mass of gas (small in comparison with the mass of the rocket) at the same speed with respect to the rockets. The kinetic...
  9. M

    How far does the block slide? (work, spring, incline)

    1. Homework Statement The system is released from rest with no slack in the cable and with the spring stretched 225 mm. Determine the distance s traveled by the 3.2-kg cart before it comes to rest (a) if m approaches zero and (b) if m = 2.5 kg. Assume no mechanical interference and no friction...
  10. Curtiss Oakley

    Problem involving energy/motion

    1. Homework Statement A ball of mass m=0.300 kg is connected by a strong massless rod of length L = 0.800 m to a pivot and held in place with the rod vertical. A wind exerts constant force F to the right on the ball as shown below. The ball is released from rest. The wind makes it swing up to...
  11. matai

    Using Integrals to Calculate the Rotational Energy of Earth

    So I found the linear velocity by using the circumference of the earth which I found to be 2pi(637800= 40014155.89meters. Then the time of one full rotation was 1436.97 minutes, which I then converted to 86164.2 seconds. giving me the linear velocity to be 465.0905584 meters/second. I know that...
  12. Benjamin Fogiel

    A rocket burns out at an altitude h above the Earth's surface

    1. Homework Statement A rocket burns out at an altitude h above the Earth's surface. Its speed v0 at burnout exceeds the escape speed vesc appropriate to the burnout altitude. Show that the speed v of the rocket very far from the Earth is given by v=(v02-v2esc)1/2 2. Homework Equations...
  13. P

    Kinetic Energy & Momentum of a Ball released from Spring

    1. Homework Statement "A spring with a spring constant "k" is compressed 10 cm from equilibrium. A ball of mass 100 g is at rest next to it. The spring then decompresses quickly back to its equilibrium position causing the ball to shoot forward. If the spring constant is 500 N/m, what is the...
  14. J

    Rank the four objects from fastest to slowest

    1. Homework Statement Rank the four objects (1kg solid sphere, 1kg hollow sphere, 2kg solid sphere and 1kg hoop) from fastest down the ramp to slowest. (Please see the attached screenshot for more details.) 2. Homework Equations KE_rot = 1/2Iw^2 (where omega = w) 3. The Attempt at a...
  15. Abimbola1987

    I Joule's first law - kinetic energy of electrical current

    Dear Sirs, If I take this explanation as being true "The heat is generated on the microscale when the conduction electrons transfer energy to the conductor's atoms by way of collisions." So a "current" must have a quantum of kinetic energy going into the conductor (resistive element) and a...
  16. J

    Moving down a ramp

    1. Homework Statement Please look at the problem attached as a screenshot. 2. Homework Equations Assuming frictionless, Ei = Ef, which means objects that are the same will end up in the same heights (so we can group A&C, B&D, and E&F). For A&C and E&F, mgh = KE_rot + KE_trans For B&D, it...
  17. J

    Solid sphere rolling along a track

    1. Homework Statement Please see the attached file. 2. Homework Equations Ei = Ef 3. The Attempt at a Solution I don't have an answer key provided, but I'd really like to verify that I'm right (or if I'm wrong, why). I think ti'd be (c) because assuming that due to inertia, B will...
  18. J

    Do A and C have same or different KE at the end?

    1. Homework Statement Please look at the attached screenshot. 2. Homework Equations Assuming the ramp is frictionless, Ei = Ef and thus mgh = KE ( = 1/2mv^2, which isn't really necessary here) 3. The Attempt at a Solution I'm okay with all other examples except for A and C. From the...
  19. J

    What velocity does a train need to go up and down the hill

    1. Homework Statement There is a train of length d and speed v. It is heading towards a hill with height h and length of each side l. What velocity requirement must be met so that the train can go up and down the hill? 2. Homework Equations Ek=m⋅v2/2 Ep=m⋅g⋅h 3. The Attempt at a Solution...
  20. DracoMalfoy

    Finding the Kinetic Energy of a particle in 2mol of nitrogen

    1. Homework Statement What is the kinetic energy of a particle in 2mol of nitrogen gas at atmospheric pressure that is within a volume of 100m^3? a. 1.27X10^-17J b. 3X10^5J c. 6.8X10^-16J d. 2.97X10^7 e. 9.9X10^-14J 2. Homework Equations PV=nRT n=Numberof particles/Na Na=6.02x10^23 R=8.13...
  21. J

    Speed or turning point using energy

    1. Homework Statement Please look at the attached screenshot. This problem is really confusing for me and I can't seem to make much sense out of it. 2. Homework Equations Ei = Ef 3. The Attempt at a Solution As you can see, I did get (a). (The other checkmarks, I guessed — there were...
  22. A

    How much work needs to be done on a piano to move it into the bed of a truck?

    1. Homework Statement Movers must push a piano onto a truck, the bed of which is a height 1.35 m above the ground. To do this they will use a frictionless ramp. If the piano has a mass of 1806.0 kg and the movers push it up the slope at a constant velocity, how much work do they need to do on...
  23. M

    Elastic collision with particles, find the kinetic energy

    1. Homework Statement A proton strikes a stationary alpha particle (4He nucleus) head-on. Assuming the collision is completely elastic, what fraction of the proton’s kinetic energy is transferred to the alpha particle? 2. Homework Equations Pi = Pf Ki = Kf 3. The Attempt at a Solution...
  24. sush

    I Why E=mc^2 is different from E=1/2 mv^2?

    Why kinetic energy is ½ m v2? Why it is different from Einstein’s equation for Energy E= m c2?
  25. F

    Distance traveled with linearly increasing kinetic energy

    1. Homework Statement An object of mass 50 kg gains 20,000,000 joules every second. Devise formulae to find the distance covered at any given point in time, and the time necessary to cover a certain distance. 2. Homework Equations 3. The Attempt at a Solution E = 20,000,000 * t V = (E *...
  26. Ennio

    I Formulating the kinetic energy of an object - helical motion

    Hi guys, I need your support to formulate the kinetic energy of an object: - having mass m [Kg] - rotating with angular velocity o [rad/sec] referred to an axis t [m] distant (and parallel) to the symmetry axis of the object - moving along the direction of its symmetry axis with a costant...
  27. Exath

    Rotation of Rigid Bodies: Rotating stick with disc on top

    1. Homework Statement A thin cylindrical rod with the length of L = 24.0 cm and the mass m = 1.20 kg has a cylindrical disc attached to the other end as shown by the figure. The cylindrical disc has the radius R = 8.00 cm and the mass M 2.00 kg. The arrangement is originally straight up...
  28. A

    I Do electromagnetic waves have potential and kinetic energy

    Do electromagnetic waves have potential and kinetic energy like springs, strings, etc. If so how are they calculated, inter-related? What is the total energy? Are the energies fluctuating over time? I am a physics hobbyist so generally the first answers should come with the least mathematics...
  29. I

    Find the launch speed of a ball in a spring mechanism

    1. Homework Statement I have a question asking me to find the launch speed of a ball (mass 0.39kg) when released by a spring mechanism made of 2 springs each with force constant 25Nm^-2. they are pulled back 12 cm. the ball is initially at rest. 2. Homework Equations v^2=u^2+2as f=ma f=kx...
  30. negative

    A Relation between boltsmann/gas constant and temperature

    so i have been trying to calculate boltsmann constant by assuming the fact that for an ideal gas the equation : PV=nRT is true. i assume that for containing each molecule the wall needs to apply a force. now here is where it get's a little weird. each molocule should be only deflected in the...
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