Had to look for the options and here is my answer. What happens when the fluid discharge of an air-operated reciprocating pump is shut, this will cause the pump to OVERSTROKE. Overstroke happens when the engine is switching in a normally-closed manner.  
        
                    
             
        
        
        
Answer:
C
Sign-Negative
Explanation:
We are given that 
Electric field =
 (Radially downward)
Acceleration=
(Upward)
Mass of charge=3 g=
kg
1kg=1000g
We have to find the magnitude and sign of  charge would have to be placed on a penny .
By newton's second law


Substitute the values then we get 

Substitute the values then we get 




C
Sign of charge =Negative
Because electric force acting  in opposite direction of electric field therefore,charge on penny will be negative.
 
        
             
        
        
        
<span>The correct answer is: (D) Generator
Explanation:
In wind-powered systems, the wind energy turns the blades around the rotor of a wind turbine. That rotor is connected to a generator that generates electricity. In other words, the kinectic energy of the wind is converted into electrical energy by using the generator in the wind-powered systems.</span>
        
                    
             
        
        
        
There are some missing data in the text of the problem. I've found them online:
a) coefficient of friction dry steel piston - steel cilinder: 0.3
b) coefficient of friction with oil in between the surfaces: 0.03
Solution:
a) The force F applied by the person (300 N) must be at least equal to the frictional force, given by:

where 

 is the coefficient of friction, while N is the normal force. So we have:

since we know that F=300 N and 

, we can find N, the magnitude of the normal force:

b) The problem is identical to that of the first part; however, this time the coefficienct of friction is 

 due to the presence of the oil. Therefore, we have:
 
        
             
        
        
        
Answer:
Photopolymerization is the term for hardening or curing the sealant or composite material by exposing the material to a curing light
Explanation:
It the process through which a photopolymer reacts to the radiations in presence of the Ultra-violet light. Photopolymers refers to those materials and liquid or the plastic resins that are hardened in presence of light source such as the lasers or the lamps. When these materials are irradiated, they undergo chemical reactions and they are hardened and become solid, and hence the process called photopolymerization. Photopolymerization is majorly used in the coating and printing industries and in also in dentistry to fill the top of teeth and prevent the cavities