Answer:
(A.) Hang curtains over the windows that will transmit sound waves and absorb light waves
The kinetic Energy has to be the same as the Energy with which the spring was stratched:
1/2×m×v^2=1/2×D×s^2
Ekin=1/2×440×0.3^2= 1/2×440×0.09=19.8. ( Of course, the kinetic Energy is normally Not calculated Like this , but in this case both Formulas have the Same solution so you can Wright it Like This)
By the way, if the spring Had Not reached its Natural length yet, you wouldnt be right if you calculate it Like above, because a Part of the Energy is still in the spring : Espring=Ekin+Espring2
A black hole is a place in space where gravity pulls so much that even light can not get out.
Answer: cork
Explanation: because the cork is less dense then the brick and Steal will just drop to the bottom
You said 2 revolutions every 0.08 seconds
1 revolution = 2pi radians.
A). The 'unit rate' is (2 rev) x (2pi / 0.08 sec) = 50pi radians/sec. =
157.1 radians per sec (rounded)
B). Radius of the wheel = 30 cm
Circumference = 2pi R = 60pi cm = 188.5 cm (rounded)
Rotation speed = 2 revs per 0.08 sec
Linear speed = 2 x 60pi cm per 0.08 sec
(120pi cm) / (0.08 sec) = 47.12 meters per sec
C). Frequency = (revs) per second
= (2) / (0.08 sec) = 25 per second .
