Question

Determine the acceleration (in m/s2) of an object which ... . 1. moves in a straight line with a constant speed of 20.0 m/s for 12.0 seconds 2. changes its velocity from 12.1 m/s to 23.5 m/s in 7.81 seconds 3. changes its velocity from 0.0 mi/hr to 60.0 mi/hr in 4.20 seconds 4. accelerates from 33.4 m/s to 18.9 m/s over a distance of 109 m

Answer 1

Answer:

1) 0 m/s²

2) 1.5 m/s²

3) 6.38 m/s²

4) -3.47 m/s²

Explanation:

The acceleration is given by:

$a=\frac{vf-vo}{t}$

1)

For the first question, the acceleration is zero, because there is no change on its velocity:

$a=\frac{(20m/s-20m/s)}{12}=0$

2)

$a=\frac{(23.5m/s-12.1m/s)}{7.81}=1.5m/s^2$

3) here we have to make an conversion:

$vo=0m/s\\vf=60.0\frac{mi}{h}*\frac{1m}{0.000621mi}*\frac{1h}{3600s}=26.8m/s$

$a=\frac{(26.8m/s-0m/s)}{4.20}=6.38m/s^2$

4) here we have to use the following formula:

$vf^2=vo^2+2*a*x\\\\a=\frac{vf^2-vo^2}{2*x}\\a=\frac{(18.9)^2-(33.4)^2}{2*(109)}=-3.47m/s^2$