The car is initially traveling north at 17.7 m/s, and after 12 s, its velocity is 14.1 m/s, still due north. This means that the direction of the car has not changed, so we can already say that the direction of the acceleration is north (if the magnitude of the acceleration is positive) or south (if the magnitude of the acceleration is negative).
To find the magnitude of the average acceleration, we must calculate the ratio between the change in velocity and the time taken:

Since the acceleration is negative, it means it is in the opposite direction to the motion of the car, therefore south. Therefore, the correct answer is
b) 0.30 m/s2, south
Answer:
7) order of vector addition B. does not affect the result
8) 13 Newton N = 12 Newton N + A. 1 Newton N
Explanation:
Answer:
A) Em = 4.41 J
B) L = 0.33m
Explanation:
A) The total mechanical energy of the block is the elastic potential energy due to the compressed spring. The gravitational energy is zero. Then you have:

k: constant's spring = 730 N/m
Δx: distance of the compression = 0.11m
You replace the values of k and Δx:

B) To find the distance L traveled by the block you take into account that the total mechanical energy of the block is countered by the work done by the friction force, and also by the work done by the gravitational energy.
Then, you have:

μ: coefficient of kinetic friction = 0.19
g: gravitational acceleration = 9.8m/s^2
M: mass of the block = 2.5kg
θ: angle of the inclined plane = 21°
You replace the values of all parameters:

hence, the distance L in which the block stops is 0.33m
Answer:
Heliocentrism is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Universe.
Explanation:
The period of a mass-spring system is:
T = 2π
T = period, m = mass, k = spring constant
Given values:
T = 8π s
k = 2 N/m
Plug in and solve for m:
8π = 2π
= 4
m/2 = 16
m = 32 kg
Choice A