Suzie (of mass 58 kg) is roller-blading down
the sidewalk going 36 miles per hour. She
notices a group of workers down the walkway
who have unexpectedly blocked her path, and
she makes a quick stop in 2
.
4 seconds.
What is Suzie’s average acceleration?
Put the 36mph into m/s units.
acceleration(final speed-oritinal speed)/time
final speed is zero.
To find Suzie's average acceleration, we need to use the equation:
Acceleration = Change in velocity / Time
First, we need to convert Suzie's speed from miles per hour to meters per second because the standard unit for acceleration is meters per second squared.
Given:
- Suzie's speed = 36 miles per hour
- Time = 2.4 seconds
Step 1: Convert speed from miles per hour to meters per second.
1 mile = 1609.34 meters (approximately)
1 hour = 3600 seconds (approximately)
Speed in meters per second = 36 miles per hour * 1609.34 meters / 1 mile * 1 hour / 3600 seconds
= (36 * 1609.34) / 3600
≈ 16.09345 m/s
Step 2: Calculate the change in velocity.
Suzie starts with a speed of 16.09345 m/s and comes to a stop, which means her final velocity is 0 m/s.
Change in velocity = Final velocity – Initial velocity
= 0 m/s - 16.09345 m/s
= -16.09345 m/s (negative because Suzie is slowing down)
Step 3: Calculate average acceleration.
Acceleration = Change in velocity / Time
= -16.09345 m/s / 2.4 s
≈ -6.70518 m/s²
Therefore, Suzie's average acceleration is approximately -6.70518 m/s².