11th Physics | Quiz: Acceleration

What kind of quantity is acceleration?

vector quantity

How do you know when to use a negative in a word problem for acceleration?

when the direction is opposite the given

(#31) A car is traveling due north at 20.4 m/s. Find the velocity of the car after 5.00 s if its acceleration is *(a)* 1.80 m/s² due north, or *(b)* 2.30 m/s² due south.

*a = [v̅f - v̅i]/[tf - ti]* *(a)* 1.80 m/s² = [v̅f - 20.4 m/s]/[5.00 s] 9 = v̅f - 20.4 *v̅f = 29.4 m/s N* *(b)* -2.30 m/s² = [v̅f - 20.4 m/s]/[5.00 s] -11.5 = v̅f - 20.4 *v̅f = 8.9 m/s S*

(#30) A jet makes a landing traveling due east with a speed of 115 m/s. If the jet comes to rest in 13.0 s, what is the magnitude and direction of its average acceleration?

*a = [v̅f - v̅i]/[tf - ti]* a = [0 - 115 m/s]/[13.0 s] a = -8.85 m/s² *magnitude: -8.85* *direction: W*

(#28) A 747 airliner reaches its takeoff speed of 180 mi/h in 30.0 s. What is its average acceleration?

*a = [∆v̅]/[∆t]* a = [180 mi/h]/[30.0 s] (180 mi/h × [1 h]/[3600 s] × [1609.34 m]/[1 mi] = 80.47 m/s) a = [80.47 m/s]/[30.0 s] *a =* 2.68 m/s²

acceleration formulas

a = [∆v̅]/[∆t] a = [v̅f - v̅i]/[tf - ti] (alternative: v̅f = v̅i + at)

velocity vs. time graph

acceleration (use formula as needed) *a = [v̅f - v̅i]/[tf - ti]* aA = [40 m/s - 0]/[2 s - 0] = 2 m/s² aB = [40 m/s - 40 m/s]/[50 s - 20 s] = 0 m/s² aC = [80 m/s - 40 m/s]/[60 s - 50 s] = 4 m/s²

acceleration

the rate of change in velocity