Recent content by midgic

  1. M

    What is the amplitude of induced EMF in a magnetic dipole antenna?

    Thank you so much for your reply. That makes sense for part (b). I think I can write it like this: (?) $$B = B_0~cos(\omega~t)$$ $$\frac{dB}{dt} = -B_0~\omega~sin(\omega~t)$$ Then $$emf = -N~B_0~(2\pi~f) \times \pi~r^2$$ And for part (c)...well as you point out, that's quite...
  2. M

    What is the amplitude of induced EMF in a magnetic dipole antenna?

    1. A magnetic dipole antenna is used to detect an electromagnetic wave. The antenna is a coil of 50 turns with radius 5.0 cm. The EM wave has frequency 870 kHz, electric field amplitude 0.50 V/m, and magnetic field amplitude 1.7 X 10-9 T. (b) Assuming it is aligned correctly, what is the...
  3. M

    2D kinematic problem: Tennis serve

    Oh, thanks for pointing this out. Then I think I can put the equation in this form: $$a*tan^2(\theta) + b*tan(\theta) + c = 0$$ Then I would use the quadratic formula to solve for tan(theta)? Is this the standard way to solve a question like this? Is there not a simpler way to find theta...
  4. M

    2D kinematic problem: Tennis serve

    Thanks a lot for your reply. This is what I tried: $$t = \frac{11.9}{47.2*cos(\theta)}$$ $$0.91 = 2.5 - 11.9*tan(\theta) - \frac{4.9*(11.9)^2}{(47.2*cos(\theta))^2}$$ But I'm not sure how to solve the final equation for theta.
  5. M

    2D kinematic problem: Tennis serve

    The initial velocity is 47.2 m/s y-component: $$0.91 = 2.5 - 47.2*sin(\theta)*t - 4.9*t^2$$ x-component: $$11.9 = 47.2*cos(\theta)*t$$ So, we have two equations and two unknowns (theta and t), but I don't see how to proceed from here. I would appreciate any help. Thanks a lot.
  6. M

    2D kinematic problem: Tennis serve

    I'm wondering about this question also. It's a question from the OpenStax AP Physics textbook. I have two equations with two unknowns (theta and t) and I'm not sure how to proceed.
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