Answer:
0 N
Explanation:
The key for solving the problem is in the sentence "moving at a constant speed in a straight line".
In fact, this means that the velocity of the sled is constant: and therefore, that its acceleration.
Newton's second law states that:
F = ma
where
F is the net force on an object
m is its mass
a is its acceleration
In this problem, we have asserted that the acceleration of the sled is zero:
a = 0
Therefore, according to the equation above, this also means that the net force on the sled is also zero:
F = 0 N
(This implies that there must be another force, must like the force of friction, that acts backward, in the opposite direction to the pull applied by the dogs).
Answer:
29.4 uN
Explanation:
The electric force between two charges can be calculated using Coulomb's Law. According to this law the force between two point charges is given as:
where k is a proportionality constant known as the Coulomb's law constant. Its value is 
Nm²/C²
r = distance between charges = 70 cm = 0.7 m
q1 = q2 = 4nC = 
C
The negative sign indicates that the charges are negative. In the formula we will only use the magnitude of the charges.
Using these values in the formula, we get:
Therefore, the magnitude of repulsive force between the given charges will be 29.4 uN
Photoautotrophs use light energy to convert carbon dioxide into organic compounds. This process is called photosynthesis. Chemoautotrophs extract energy from inorganic compounds by oxidizing them and use this chemical energy, rather than light energy, to convert carbon dioxide into organic compounds
