Posts by amena

Total # Posts: 9

  1. Physics

    You are flying in an ultra-light aircraft at a speed of 41.4 m/s. An eagle, whose speed is 21.7 m/s, is flying directly toward you. Each of the given speeds is relative to the ground. The eagle emits a shrill cry whose frequency is 3680 Hz. The speed of sound is 330 m/s. What ...
  2. Physics

    I got 0.193 half-lives. Does this answer make sense??
  3. Physics

    A sample starts with 1000 radioactive atoms. How many half-lives have elapsed when 875 atoms have decayed? I am not sure how to solve this, please help!!
  4. Physics

    For b) would the answer be the same number of N atoms of X, because the box is in a perfect vacuum?
  5. physics

    Over a time interval of 1.98 years, the velocity of a planet orbiting a distant star reverses direction, changing from +21.9 km/s to -17.2 km/s. Find (a) the total change in the planet's velocity (in m/s) and (b) its average acceleration (in m/s2) during this interval. ...
  6. physics

    Over a time interval of 1.98 years, the velocity of a planet orbiting a distant star reverses direction, changing from +21.9 km/s to -17.2 km/s. Find (a) the total change in the planet's velocity (in m/s) and (b) its average acceleration (in m/s2) during this interval. ...
  7. physics

    A boy jumps from rest, straight down from the top of a cliff. He falls halfway down to the water below in 0.993 s. How much time passes during his entire trip from the top down to the water? Ignore air resistance. Pls help and explain!
  8. math

    Write in exponential notation x*x*x*x*x*y*z
  9. physics

    A solid ball is released from rest and slides down a hillside that slopes downward at an angle 52.0 from the horizontal.What minimum value must the coefficient of static friction between the hill and ball surfaces have for no slipping to occur?