Answer:
a) The car's acceleration during the first 20 s = 1 m/s²
b) Net force applied by the engine during the first 20 s = 2000 N
c) The car's acceleration from 20 s to 40 s = 0 m/s²
d) Net force applied by the engine during 20 s to 40 s = 0 N
e) The car's acceleration from 40 s to 50 s = -2 m/s²
f) The net force applied by the engine during the time 40s to 50s = -4000 N
Step-by-step explanation:
The mass of the car, m = 2000 kg
a) Acceleration in the first 20 seconds
In the first 20 seconds, the car's speed increases from 0 m/s to 20 m/s
The final velocity, v = 20 m/s
The initial velocity, u = 0 m/s
Time taken, t = 20 s
Using the equation v = u + at
20 = 0 + 20a
20 = 20a
a = 20/20
a = 1 m/s²
b) Net force applied applied by the engine during the first 20 seconds
F = ma
F = 2000(1)
F = 2000 N
c) Acceleration from 20 s to 40 s
Note that the velocity of the car does not change (is constant) between 20 s and 40 s. This means that the car does not accelerate within this time interval
Acceleration from 20 s to 40 s = 0 m/s²
d) Net force applied by the engine during 20 s to 40 s
a = 0 m/s²
F = ma
F = 2000(0)
F = 0 N
e) The car's acceleration from 40 s to 50 s
Within this time interval, the car decelerates from 20 m/s to 0 m/s
The initial velocity, u = 20 m/s
The final velocity, v = 0 m/s
Time taken, t = 50 s - 40 s
t = 10 s
Using the equation v = u + at
0 = 20 + 10a
10a = -20
a = -20/10
a = -2 m/s²
The car's acceleration from 40 s to 50 s = -2 m/s²
f) The net force applied by the engine during this time (40s to 50s)
a = -2 m/s²
F = ma
F = 2000(-2)
F = -4000N