A sailing boat has a forward force of 300N from the wind in its sails. It is travelling at a constant speed. What is the total force acting backward on the sailing boat?

-300 N

Explanation:

The key words here are "constant speed". By this, we mean that all the forces on the object (the sailing boat here) are balanced - so they must be equal in magnitude.

Here, we know that the boat has a forward force of 300 N. Because the forces are balanced, then the backward force must also have a force with magnitude 300 N.

However, note that because the backward force is in the opposite direction as the forward force, we must put a negative sign on the 300. So our answer is: -300 N.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.