Answer: 4
The mechanical advantage is the ratio of the force exerted by the object to the force applied to do work on it.
Here, Jeff tried to lift a rock weighing 600 pounds by wedging board under the rock. Jeff who weighs 150 pounds uses all his weight to exert force on lever and lift rock.
Mechanical advantage, 
Therefore, the mechanical advantage that lever provided to Jeff in lifting rock is 4.
Answer:
, where the minus indicates the direction is opposite to that of the throw.
Explanation:
a)
Since MKS stands for meter-kilogram-second and we know that:



We can write that:



These are conversion factors, equal to 1, so multiplying our results by them won't change their value, only their units.
So we have that:



b)
Newton's 2nd Law tells us that F=ma, and the definition of acceleration is
, so we have:

Taking the throw direction as the positive one, for our values we have:

Kingdom Animalia includes only organisms that are heterotrophic.
When the heat source is removed from a fluid, convection currents in the fluid will eventually distribute heat uniformly throughout the fluid. When all of the fluid is at the same temperature, convection currents will stop.
Answer:
I would say both
Explanation:
Each silicon atom has four valence electrons which are shared, forming covalent bonds with the four surrounding Si atoms.
Carbon contains four electrons in its outer shell. Therefore, it can form four covalent bonds with other atoms or molecules. The simplest organic carbon molecule is methane (CH4), in which four hydrogen atoms bind to a carbon atom (Figure 1).