Answer:
The plate's surface charge density is 
Explanation:
Given that,
Speed = 9800 km/s
Distance d= 75 cm
Distance d' =15 cm
Suppose we determine the plate's surface charge density?
We need to calculate the surface charge density
Using work energy theorem


Here, final velocity is zero
...(I)
We know that,


...(II)
From equation (I) and (II)

Charge is negative for electron

Put the value into the formula


Hence, The plate's surface charge density is 
Answer:(a) 50 N
(b)38.34 N
Explanation:
Given
Maximum tension(T) in line 50 N
(a)If line is moving up with constant velocity i.e. there is no acceleration
This will happen when Tension is equal to weight of Fish
T-mg=0
T=mg
Maximum weight in this case will be 50 N
(b)acceleration of magnitude 
T-mg=ma


m=3.91
Therefore weight is 
Answer: (1) The resistance increases and the current decreases.
Explanation:
When the temperature of the filament increases, the vibrational energy of the constituent atoms increases which leads to increase in inter-atomic collision. Thus, the resistance would increase. The increases in resistance would obstruct the flow of charges more leading to decrease in the value of the current.
Hence, when the temperature of the filament increase, the resistance increases and current decreases.
Answer:
X= 700 Joules
Explanation:
The question asked about the efficiency of the work done.
The formula for efficiency is: Efficiency = (Useful output / input work) * 100%
The useful output given in the question is 140J, the question asked for input work. Let X be the input work. It is also given that the efficiency is 20%.
Using the formula of efficiency,
20 = (140/X) * 100
So, we simply solve the above equation.
X= 140*100/20
X= 700 Joules
To begin to lift the car, a hydraulic jack must produce <em>more than 9,800N</em> of force.
To keep the car in position once it is lifted, the jack must produce <em>exactly 9,800N</em> of force.