Answer:
[tex]\boxed {\boxed {\sf B. \ -8.9 \ m/s^2}}[/tex]
Explanation:
Acceleration is found by dividing the change in velocity by the change in time.
[tex]a=\frac {v_f-v_i}{t}[/tex]
The parachute slows from 85 m/s to 45 m/s. Therefore, the final velocity is 45 meters per second and the initial velocity is 85 meters per second. The time is 4.5 seconds.
[tex]v_f= 45 \ m/s \\v_i= 85 \ m/s \\t= 4.5 \ s[/tex]
Substitute the values into the formula.
[tex]a= \frac {45 \ m/s- 85 \ m/s}{4.5 \ s}[/tex]
Solve the numerator and subtract.
[tex]a= \frac {-40 \ m/s}{4.5 \ s}[/tex]
Divide.
[tex]a=-8.888888889 \ m/s/s[/tex]
If we round this to the nearest tenth, the 8 in the hundredth place tells us to round the 8 up to a 9.
[tex]a \approx -8.9 \ m/s/s= -8.9 \ m/s^2[/tex]
The acceleration of the parachute is approximately -8.9 meters per square second. The value is negative because the parachute is slowing down.
