#1 and #3 are correct.
#3 is slightly goofy.
The problem is not that there's no air to vibrate your eardrum.
The problem with no air is that there's nothing to ever bring the sound
to your head, even if you're only a foot away from the source. There
are just NO SOUND WAVES going on at all.
The acceleration of gravity is 9.8 m/s². This simply means that when anything falls, its downward speed keeps increasing, and it falls 9.8 m/s faster every second than it fell 1 second earlier.
After 3 seconds of falling, the object is falling at (3 x 9.8 m/s) = 29.4 m/s faster than at the beginning of the 3 seconds. If it had no vertical speed at the beginning of the 3 seconds, then THAT's its speed after 3 seconds . . . . . <em>29.4 m/s</em> downward.
As far as being thrown horizontally off the cliff . . . that has no effect on it vertical speed. Horizontally, it doesn't matter whether it rolls gently over the edge, or somebody throws it horizontally, or it gets shot horizontally out of a high power rifle. It hits the ground at the same time and with the same speed in every case.
Answer:
0.00198 secs
Explanation:
Parameters given:
Mass of baseball, m = 0.14 kg
Initial velocity of baseball, u = 33.6 m/s
Force applied to baseball, F = -5000 N
(The force is applied in an opposite direction to the initial velocity)
Final velocity, v = -37 m/s
Using the impulse-momentum theory, we have that the impulse applied to the baseball is equal to the change in momentum of the baseball:
FΔt = m(v - u)
Time interval, Δt, will be given as:
Δt = 
Δt = 
Δt = 
Δt = 
Δt = 
The bat and the baseball were in contact for 0.00198 secs.
Answer:
Speed of the approaching train = 15.45 m/s
Explanation:
Given:
Frequency F0 = 220 Hz
Beat frequency F1 = 10.0 Hz
Find:
Speed of the approaching train
Computation:
Approaching frequency F2 = 220 + 10.0 Hz
Approaching frequency F2 = 230 Hz
Doppler shift;
F = [(v+v0)/(v-vS)]F0
230 = [(340+v0)/(340-0)]220
V0 = 15.45 m/s
Speed of the approaching train = 15.45 m/s
