Answer:
The liquid is vaprizing at point C
Mechanical advantage of a machine is the ratio of the output force over the input force or M=Fo/Fi. Since M=1, Fi=Fo, or the input force is equal to the output force. This means that to raise the refrigerator that weighs 900 N, we need the same input force of 900 N, or Fo=Fi=900 N.
Answer = 30,000 N
EXPLANATION
Applying Newton’s second of law of motion, which in summary, states that t<span>he acceleration of an object... is directly proportional to the magnitude of the net force... and inversely proportional to the mass of the object.
</span><span>
Therefore, Force = Mass * Acceleration
F = ma
Mass, m = </span><span>3,000 kg
</span>Acceleration, a = <span>10 m/s</span>²<span>
</span>Force, F = 3,000 × 10
= 30,000 N
(a) The magnitude of force that the positive charge exerts on the negative charge is - 2.209 N.
(b) If the negative charge is doubled, then the force will also get doubled.
The new force will be F = -4.418 N.
Explanation:
The force acting between two charged particles separated by a distance is termed as Coloumb's force or electrostatic force. It can be termed as electrostatic force of attraction if the the force acting between the charges are oppositely charged. And it can be termed as electrostatic force of repulsion if the charges are similar or like charges.
In the present case, there is a positive and negative charge, so electrostatic force of attraction will be acting between them. As per Coloumb's law, the electrostatic force of attraction is directly proportional to the product of charges and inversely proportional to the square of distance of separation.

Here, k is the constant of proportionality which is equal to 9 ×
and Q, q are the two charges, d is the distance of separation.
So here Q = 5.5 ×
and q = - 3.5 ×
and d = 0.28 m
Then, 
So the magnitude of force that the positive charge exerts on the negative charge is - 2.209 N.
(b) If the negative charge is doubled, then the force will also get doubled.
The new force will be F = -4.418 N.
Answer:
8.362m/s
Explanation:
Given data
Mass m1= 7.77kg
Velocity v1= 7.77m/s
Mass m2= 8.88kg
Velocity v2= 8.88m/s
Apply the law of conservation of momentum for inelastic collision we have
m1v1+m2v2= (m+m2)V
7.77*7.77+ 8.88*8.88= (7.77+8.88)V
60.3729+78.8544= 16.65V
139.2273= 16.65V
Divide both sides by 16.65
V= 139.2273/16.65
V= 8.362m/s
Hence the final velocity is 8.362m/s