Answer:
light waves can travel in vacuum but sound waves require a medium to travel
also light waves are electromagnetic waves while sound waves are mechanical, light waves are transverse waves while sound waves are longitudinal waves
We are told that 4.0
complete waves pass a fixed point in 10 seconds. Using these data, we can find the frequency of the wave, which is given by the number of complete cycles per second:
Now we can find the period of the wave, which is the reciprocal of the frequency:
So, the correct answer is (3) 2.5 s.
<span>0.506 m/s^2
Given the arrangement of rope and the man, he's effectively suspended by a rope from a frictionless pulley. So he's pulling the rope with a force of 371 n causing him to be pulled upwards by his arms. Additionally, the rope goes up to the pulley and back down to the man causing an additional 371 n of force pulling him upwards. So the total force being used to lift the man is 742 n.
Additionally, the man is being pulled downwards by gravity at 9.80 m/s^2. And since he masses 72.0 kg, the downward force in newtons is 72.0 kg * 9.80 m/s^2 = 705.6 n downward.
So the total force being exerted on the man is
742 n - 705.6 n = 36.4 n
To calculate his acceleration, simply divide the number of newtons applied by his mass.
36.4 kg m/s^2 / 72.0 kg = 0.505556 m/s^2
And round to 3 significant figures.
0.505556 m/s^2 = 0.506 m/s^2</span>
Answer:
1.22kg
Explanation:
info given:
height (h) = 7.25m
g = 9.81m/s^2
PE = mgh
Plug in info and solve for m.
m(9.81m/s^2)(7.25m) = 87.4J
m = 1.22kg