This document discusses average acceleration while turning. It defines that uniform motion has constant velocity in both magnitude and direction, while turning involves a change in direction and therefore acceleration. The equation for average acceleration while turning is given as aTurning = Δv/Δt. An example problem is worked out, finding the average acceleration while Sally turns from running south to east over 4 seconds without changing her speed. Practice problems are then provided applying the concept.

1. Lesson 7
Average Acceleration
While Turning
Done By Example
No Reference Pages

2. Uniform motion was previously defined as beingUniform motion was previously defined as being
constant velocity. And constant velocity requiresconstant velocity. And constant velocity requires
thatthat bothboth magnitudemagnitude andand directiondirection bebe constantconstant..
 If a car is moving at a constant 100 km/h aroundIf a car is moving at a constant 100 km/h around
a circular bend in the road, it will experiencea circular bend in the road, it will experience
acceleration because it is constantly changingacceleration because it is constantly changing
direction.direction.
 When aWhen aTurningTurning is calculated, it is in theis calculated, it is in the samesame
 direction asdirection as ΔΔvv and is anand is an averageaverage value (why?)value (why?)
 The equation used isThe equation used is aaTurningTurning == ΔΔv/v/ ΔtΔt

3. Sally is running south at 2.5 m/s. She then changes directionSally is running south at 2.5 m/s. She then changes direction
and runs east at the same pace. If it takes her 4 s to turn,and runs east at the same pace. If it takes her 4 s to turn,
determinedetermine aaTurningTurning
 G: vG: v11 = 2.5m/s [S], v= 2.5m/s [S], v22 ==
2.5 m/s [E],2.5 m/s [E], Δt = 4sΔt = 4s
 R:R: aaTurningTurning
 A:A: Δv = vΔv = v22 – v– v11 (draw vector(draw vector
diagram), then use the eq’ndiagram), then use the eq’n
for afor aturningturning
 Solution:Solution:
 Since the vSince the v22 and – vand – v11 areare ⊥⊥
to each other, and haveto each other, and have
the same magnitude,the same magnitude, thethe
angle θ is 45angle θ is 4500
 Statement:Statement:
∴∴ aaTurningTurning == 0.9 m/s2
[NE]
a T U R N I N G
= v 2
- v 1
t 2
- t 1
= 2 . 5 2
+ 2 . 5 2
[ N E ]
4
N
W E
v 2 = 2 . 5 m / s
-v1=2.5m/s
v

4. Practice Problems
Questions from McGraw-Hill TB
1.1. A car is traveling atA car is traveling at 50.0 km/h [N] when it makeswhen it makes
a turn which takesa turn which takes 5.0 s and then travels west atand then travels west at
the same pace. Det’m:the same pace. Det’m: Δv andand aTurning..
Ans. 71 km/h [SW], 3.9 m/s2
[SW],
2. A marble is rolling across a table with a velocity
of 21 cm/s [E]. The marble is tapped by a ruler
900
to its initial DOM. The marble accelerates in
the direction of the tap for 0.50 s at a rate of 56
cm/s2
. Det’m: v2
Ans. 35 cm/s [530
away from original direction]