Answer:
1)
is<u> positive.</u>
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2) 
Explanation:
<h2><u>
Part 1:</u></h2>
<u></u>
The charged rod is held above the balloon and the weight of the balloon acts in downwards direction. To balance the weight of the balloon, the force on the balloon due to the rod must be directed along the upwards direction, which is only possible when the rod exerts an attractive force on the balloon and the electrostatic force on the balloon due to the rod is attractive when the polarities of the charge on the two are different.
Thus, In order for this to occur, the polarity of charge on the rod must be positive, i.e.,
is <u>positive.</u>
<u></u>
<h2><u>
Part 2:</u></h2>
<u></u>
<u>Given:</u>
- Mass of the balloon, m = 0.00275 kg.
- Charge on the balloon,

- Distance between the rod and the balloon, d = 0.0640 m.
- Acceleration due to gravity,

In order to balloon to be float in air, the weight of the balloom must be balanced with the electrostatic force on the balloon due to rod.
Weight of the balloon, 
The magnitude of the electrostatic force on the balloon due to the rod is given by

is the Coulomb's constant.
For the elecric force and the weight to be balanced,

Answer:
spring deflection is x = (v2 / R + g) m / 4
Explanation:
We will solve this problem with Newton's second law. Let's analyze the situation the car goes down a road and finds a dip (hollow) that we will assume that it has a circular shape in the lower part has the car weight, elastic force and a centripetal acceleration
Let's write the equations on the Y axis of this description
Fe - W = m 
Where Fe is elastic force, W the weight and
the centripetal acceleration. The elastic force equation is
Fe = - k x
4 (k x) - mg = m v² / R
The four is because there are four springs, R is theradio of dip
We can calculate the deflection (x) of the springs
x = (m v2 / R + mg) / 4
x = (v2 / R + g) m / 4
Answer:
605 km
Explanation:
Hello
the same units of measure should be used, then
Step 1
convert 42 m/s ⇒ km/h
1 km =1000 m
1 h = 36000 sec


Step 2
find kilometers traveled after 4 hours

V,velocity
s, distance traveled
t. time
now, isolating s

and replacing

S=604.8 Km
Have a great day
Your answer would be total number of atoms! This is because when you have these equations which require total number of atoms.