A construction crew uprights an overturned backhoe on a steep hill, whereupon it
ID: 801773 • Letter: A
Question
A construction crew uprights an overturned backhoe on a steep hill, whereupon it promptly rolls down the hill. (See video "help" button at the bottom of this question to understand the situation better.) Let's suppose the backhoe picks up speed until it reaches level ground and starts slowing down, so that its velocity vs time is as shown m the graph below. Answer the questions following the graph. Assume that all numbers from the graph are good to plusminus 2%. Assume that the deceleration continues past the edge of the graph until the backhoe stops. What is the backhoe s average velocity m the first 3 s? What is the backhoe s average acceleration between t = 0 s and t=3 s? What is the backhoe s average acceleration after it reaches the level ground? How far away is the level ground from where the backhoe started? How far does the backhoe travel on the level ground before coining to a stop?Explanation / Answer
As seen from the graph the backhoe's average velocity in the first 3 sec=11m/s
Acceleration= Rate of change in velocity
velocity at t=0 is 0
velcity at t=3 is is11m/s
therefore acceleration=11-0/3-0
=11/3
=3.6m/s2
Since when the backhoe is on a steep hill its speed increases abruptly and then when it reaches the level ground its speed starts decreasing
This speed when it reaches level ground=11m/s
acceleation=speed/time
=11/3=3.6m/s2
distance=speed * time
Speed at which backhoe started=11m/s
time at which backhoes started=3s
Distance=11*3=33m
So level ground is 33 m from where backhoe started
Backhoe stopped after reaching speed=6m/s
backhoe stopped after time=12s
distance travelled by backhoe before stopping=speed*time
=6*12=72m
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