Question

A car traveling at 26 m/s starts to decelerate steadily it comes to a complete stop in 7 seconds. What is its acceleration?

Answer 1

First,
Vi= 26 m/s ( initial Velocity)
Vf= 0 m/s ( Final Velocity) because it comes to stop
t= 7 s
a= ? the acceleration must be in a negative sign because it is decelerated
second,
\[Xf-X0=Vi \times t + (1/2) \times a \times t^2\]
solve the equation for a
\[a=2( \Delta x - Vi \times t )/t^2\]
add this equation to this \[Vf = Vi + a \times t \]

then solve for x and find the position

once you find the position
solve for the acceleration by this formula
\[Vf^2 = Vi^2 + 2a \Delta x\]minus sign indicates that the acceleration is decreased.

The answer is \[a = -3.71 m/s^2\]

Answer 2

thank you so much! I understand now