Question

magnitude and direction of force quick check
which of the following scenarios accurately describes magnitude and direction? (1 point)
a car traveling northward with 5 kn of force could be brought to a stop by a northward force of 5 kn.
a car traveling northward with 5 kn of force could be brought to a stop by a southward force of 5 kg.
a car traveling northward with 5 kn of force could be brought to a stop by a southward force of 10 kn.
a car traveling northward with 5 kn of force could be brought to a stop by a southward force of 5 kn.

Explanation:

1. Analyze Option 1: A northward force on a northward - moving car will accelerate it northward, not stop it. So this is incorrect.
2. Analyze Option 2: The unit of force is newtons (or kilonewtons), but here a force is given in kilograms (which is a unit of mass). So this is incorrect.
3. Analyze Option 3: A southward force of 10 kN on a northward - moving car with a 5 kN northward force will result in a net force of \(F_{net}=10\space kN - 5\space kN = 5\space kN\) southward. This will not bring the car to a stop (it will accelerate southward). So this is incorrect.
4. Analyze Option 4: A southward force of 5 kN on a northward - moving car with a 5 kN northward force will result in a net force of \(F_{net}=5\space kN- 5\space kN = 0\space kN\). According to Newton's first law, if the net force is zero, the object will come to a stop (assuming it was moving with a force - balanced situation before, but in this case, the applied forces balance out the northward force of the car's motion). Also, the direction of the stopping force is southward (opposite to the car's motion) and the magnitude is 5 kN (equal to the car's northward force to balance it).

Answer:

D. A car traveling northward with 5 kN of force could be brought to a stop by a southward force of 5 kN. (Here we assume the last option is D, following the order of the options as presented: first option A, second B, third C, fourth D)