Answer:
The speed of proton when it emerges through the hole in the positive plate is
.
Explanation:
Given that,
A parallel-plate capacitor is held at a potential difference of 250 V.
A A proton is fired toward a small hole in the negative plate with a speed of, 
We need to find the speed when it emerges through the hole in the positive plate. It can be calculated using the conservation of energy as :

So, the speed of proton when it emerges through the hole in the positive plate is
.
Go to slader.com and type in the full name of the text book and page number. It should have the andwers
<h2>
Density of the unknown liquid is 771.93 kg/m³</h2>
Explanation:
An empty graduated cylinder weighs 55.26 g
Weight of empty cylinder = 55.26 g = 0.05526 kg
Volume of liquid filled = 48.1 mL = 48.1 x 10⁻⁶ m³
Weight of cylinder plus liquid = 92.39 g = 0.09239 kg
Weight of liquid = 0.09239 - 0.05526
Weight of liquid = 0.03713 kg
We have
Mass = Volume x Density
0.03713 = 48.1 x 10⁻⁶ x Density
Density = 771.93 kg/m³
Density of the unknown liquid is 771.93 kg/m³