Answer:
c
Explanation:
a, b, and d are examples of moving forward
 while c is moving backwards. 
 
        
                    
             
        
        
        
If dirt and grease were good conductors of electrical current, then we could make wire 
out of dirt and grease instead of expensive copper.  Sadly, they're not. So a coating of 
dirt and grease on the wire can have a substantial impact on the connection, and can 
even block the flow of current across the connection completely.  Moreover, in the case 
where the ends of the wires are to be soldered, solder does not adhere to dirty wire.
        
                    
             
        
        
        
Refer to the diagram shown below.
Assume that
(a) The piano rolls down on frictionless wheels,
(b) Wind resistance is negligible.
The distance along the ramp is
d = (1.3 m)/sin(22°) = 3.4703 m
The component of the piano's weight along the ramp is
mg sin(22°)
If the acceleration down the ramp is a, then
ma = mg sin(22°)
a = g sin(22°) = (9.8 m/s²) sin(22°) = 3.671 m/s²
The time, t, to travel down the ramp from rest is given by
(3.4703 m) = 0.5*(3.671 m/s²)*(t s)²
t² = 3.4703/1.8355 = 1.8907
t = 1.375 s
Answer: 1.375 s
 
        
        
        
Answer:
Explanation:
Given that 
F=2x³
Work is given as 
The range of x is from x=0 to x=D
W=-∫f(x)dx
Then,
W=-∫2x³dx from x=0 to x=D
W=- 2x⁴/4 from x=0 to x=D
W=-2(D⁴/4-0/4)
W=-D⁴/2
W=1/2D⁴
The correct answer is F