Answer:
An electric bell is placed inside a transparent glass jar. The bell can be turned on and off using a switch on the outside of the jar. A vacuum is created inside the jar by sucking out the air. Then the bell is rung using the switch. What will we see and hear?
A.
We’ll see the bell move, but we won’t hear it ring.
B.
We won’t see the bell move, but we’ll hear it ring.
C.
We’ll see the bell move and hear it ring.
D.
We won’t see the bell move or hear it ring.
E.
We’ll see the sound waves exit the vacuum pump.
Explanation:
so, the answer to the question is
A.
We'll see the bell move, but we won’t hear it ring.
In object in motion stays in motion; speed
The 4 significant figures of 31,546,000 are all 8 of the digits.
According to the conservation of mechanical energy, the kinetic energy just before the ball strikes the ground is equal to the potential energy just before it fell.
Therefore, we can say KE = PE
We know that PE = m·g·h
Which means KE = m·g·h
We can solve for h:
h = KE / m·g
= 20 / (0.15 · 9.8)
= 13.6m
The correct answer is: the ball has fallen from a height of 13.6m.
