Answer:
Choice A: approximately 
, assuming that the two pistons are connected via some confined liquid to form a simple machine.
Explanation:
Assume that the two pistons are connected via some liquid that is confined. Pressure from the first piston:
.
By Pascal's Principle, because the first piston exerted a pressure of 
on the liquid, the liquid will now exert the same amount of pressure on the walls of the container.
Assume that the second piston is part of that wall. The pressure on the second piston will also be . In other words:
.
To achieve a force of 
, the surface area of the second piston should be:
.
Answer:
μ = 0.309
Explanation:
coefficient of kinetic friction is defined as the ratio of two forces, friction force and the normal force acting on the object.
θ = arctan(15/100)= 8.531⁰
In the vertical direction:
N = mgcosθ = 100 *9.8 *cos(8.531) = 970N
law of conservation of energy implies
mgsinθ - μNx = 1/2m(v₂²-v₁²)
100*9.8*sin (8.531) - μ(970*2) = 1/2(100)(0²-3²)
150.6 - 1940μ = 450
- 1940μ = -600.6
μ = 0.309
Answer:
Explanation:
The inital electrostatic force between the two spheres is given by:
where
is the initial force
k is the Coulomb's constant
q1 and q2 are the charges on the two spheres
r is the distance between the two spheres
The problem tells us that the two spheres are moved from a distance of r=20 cm to a distance of r'=10 cm. So we have
Therefore, the new electrostatic force will be
So the force has increased by a factor 4. By using , we find
Correct answer choice is :
C) To see if samples contain the target dna
Explanation:
In many North American rivers, populations of various kinds of non-native cyprinid fishes are present, including black carp, grass carp, bighead carp, silver carp, common carp, and goldfish. All six of these classes are found in the Mississippi River basin and following their aggression has shown complex, especially where wealth is low. The bighead carp is a species of freshwater fish, one of several Asian carps. It is one of the most intensively exploited fishes in aquaculture, with a yearly global product of over three million tonnes in 2013, mostly from China.
