Answer:
The extension of a material or a spring is its increase in length when pulled. Hooke’s Law says that the extension of an elastic object is directly proportional to the force applied to it. In other words:
Explanation:
 
        
                    
             
        
        
        
Answer: FR=2.330kN
Explanation:
Write down x and y components. 
Fx= FSin30°
Fy= FCos30°
Choose the forces acting up and right as positive. 
∑(FR) =∑(Fx )
(FR) x= 5-Fsin30°= 5-0.5F
(FR) y= Fcos30°-4= 0.8660-F
Use Pythagoras theorem
F2R= √F2-11.93F+41
Differentiate both sides
2FRdFR/dF= 2F- 11.93
Set dFR/dF to 0
2F= 11.93
F= 5.964kN
Substitute value back into FR
FR= √F2(F square) - 11.93F + 41
FR=√(5.964)(5.964)-11.93(5.964)+41
FR= 2.330kN
The minimum force is 2.330kN
 
        
             
        
        
        
The answer of question 1 is:
 C. The gravitational force becomes 16 times less.
The answer of question 2 is:
A. The gravitational force is 12 times larger.
The answer of question 3 is :
A. The new gravitational force is 9 times stronger than the old one.
The answer of question 4 is:
D. 8 times more.
 
        
             
        
        
        
Answer:
The speed of the car when load is dropped in it is 17.19 m/s.
Explanation:
It is given that,
Mass of the railroad car, m₁ = 16000 kg
Speed of the railroad car, v₁ = 23 m/s
Mass of additional load, m₂ = 5400 kg
The additional load is dropped onto the car. Let v will be its speed. On applying the conservation of momentum as :



v = 17.19 m/s
So, the speed of the car when load is dropped in it is 17.19 m/s. Hence, this is the required solution.