- #1
Andy_ToK
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Homework Statement
Q1. A little girl is holding a helium-filled balloon on a string while
riding in a closed elevator going down a very tall building at
constant speed. The elevator shaft is maintained under vacuum.
Suddenly the elevator cable snaps, sending the elevator
into free fall. In her surprise the girl let's go of the string. She
is even more surprised to see
(a) the balloon rising.
(b) the balloon floating downward.
(c) the balloon remaining stationary.
(d) the balloon bouncing slowly between the floor and the
ceiling.
Homework Equations
Newton's 2rd and 3rd laws
The Attempt at a Solution
The answer is C which confuses me.
That means the balloon itself is accelerating in a stationary frame, then there must be some force acting on the balloon. Would it be the air in the elevator that is exerting the constant force on the balloon?
Homework Statement
Question 10
At the shallow end of a swimming pool, the water is 70.0
cm deep. The diameter of the cone of light emerging from
the water into the air above, emitted by a light source 10.0
cm in diameter at the bottom of the pool and measured by an
observer on the edge of the pool 2.50 m away, is’
(a) 1.60 m. (b) 1.70 m.
(c) 1.75 m. (d) 1.80 m.
Homework Equations
n1sin(a1)=n2sin(a2)
The Attempt at a Solution
Sorry, but i don't get waht it means by "light cone" in the question
Thanks in advance!