Dr Tony Allision hypothesize that the sickle cell disease is connected with malaria. The disease carried by the mosquito is more common in coastal area and near Lake Victoria while it is less common in the highlands. He made a further hypothesis that sickle cell disease is common in areas where malaria is also common.
Answer:
The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases
Answer:

Explanation:
m = Mass of object = 
mg = Weight of object = 20 N
g = Acceleration due to gravity = 
v = Final velocity = 15 m/s
u = Initial velocity = 0
d = Distance moved by the object = 150 m
= Angle of slope = 
f = Force of friction
fd = Work done against friction
The force balance of the system is

The work done against friction is
.