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w1NE · 2008-01-31 01:04:37

Greetings all, I am currently experiencing problems in solving this problem. Please take a look and respond is possible with the answer and short explanation.

Bats use echolocation to determine their distance from objects they cannot easily see in the dark. The time between the emission of a high-frequency sound pulse (a click) and the detection of its echo is used to determine such distances. A bat, flying at a constant speed of 19.4 m/s in a straight line toward a vertical cave wall, makes a single clicking noise and hears the echo 0.17 s later. Assuming that she continued flying at her original speed, how close was she to the wall when she received the echo? (assume the speed of sound is 343 m/s)

Martin · 2008-02-01 08:06:10

Knowing the time that elapsed before the echo was returned and the speed of sound, you should be able to calculate the round trip distance of the emitted click. If the bat were not moving, this distance would be twice the distance between the bat and the wall, say 2D.

But the bat was moving, flying at a constant speed. Knowing that speed along with the time that elapsed before the echo was returned, you can determine how much distance the bat traveled before receiving the echo. If you call that distance d, then the round trip distance of the emitted click is 2D-d, and the bat is D-d meters from the wall when she receives the echo.

jacqui43128 · 2008-02-04 05:59:39

I need help with this problem.

A 0.03 kg bullet hits a steel plate and melts and splatters on impact. Assuming that the bullet receives 80% of the collision energy, at what mininum speed must it be traveling to melt on impact. (Assume the bullet and the steel plate are initially at 21 degrees celsius.)

I found this equation for kinetic energy 1/2 mv2 and all of it is transformed to heat so Q = mc(change in temp), but I don't know the specific heat of steel, and I don't know how to go backwards to find velocity.

Can you give me any hints?

Chris · 2008-02-11 14:06:22

jacqui43128 wrote:
I need help with this problem.

Can you give me any hints?

You should start a new thread.

favydee · 2008-03-25 21:06:23

Pls can some one help me out with this problem?
"An athlete was training on a field. at th begining t(1)=0, from the mark 0m, he starts running till a point 200m, he stopped for a while and later continued to run till point 400m, and returns to the point 100m,where the time spent t(2)=100s. Calculate(A) The average velocity or the runner at instants t(1) and t(2); (B) calculate the the average scalar velocity at that interval".

Martin · 2008-03-26 02:14:55

favydee wrote:
Pls can some one help me out with this problem?
...

As Chris said to jacqui43128, above, "You should start a new thread."

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#1 2008-01-31 01:04:37

Displacement, velocity and speed HW problem.

#2 2008-02-01 08:06:10

Re: Displacement, velocity and speed HW problem.

#3 2008-02-04 05:59:39

Re: Displacement, velocity and speed HW problem.

#4 2008-02-11 14:06:22

Re: Displacement, velocity and speed HW problem.

jacqui43128 wrote:

#5 2008-03-25 21:06:23

Re: Displacement, velocity and speed HW problem.

#6 2008-03-26 02:14:55

Re: Displacement, velocity and speed HW problem.

favydee wrote:

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