Answer:
The maximum acceleration experienced by the sprinter is and it is experienced in the first phase when the sprinter starts his sprint.
Explanation:
Since the sprinter attains a final speed of 34 km/h in runing 200 meters while starting from rest we have
Using the third equation of kinematics we have
where
v is the final speed
u is the initial speed
a is the acceleration
s is the distance covered
Since it is given that sprinter starts from rest thus u= 0 m/s and v= 34 km/h = 9.4m/s this speed is attained at s = 78 m
Applying values in the above equation we get
Since after that the sprinter moves at a constant velocity thus in that phase it's acceleration is
Now since the sprinter decelerates to 30 km/h or 8.33 m/s in final 63 meters thus the deceleration experienced is again found by third equation of kinematics as
Upon comparing the maximum acceleration experienced by the sprinter is
I think it’s A
Hope I helped
Answer:
Yes, fracture will occur
Explanation:
Half length of internal crack will be 4mm/2=2mm=0.002m
To find the dimensionless parameter, we use critical stress crack propagation equation
and making Y the subject
Where Y is the dimensionless parameter, a is half length of crack, K is plane strain fracture toughness, is critical stress required for initiating crack propagation. Substituting the figures given in question we obtain
When the maximum internal crack length is 6mm, half the length of internal crack is 6mm/2=3mm=0.003m
and making K the subject
and substituting 260 MPa for while a is taken as 0.003m and Y is already known
Therefore, fracture toughness at critical stress when maximum internal crack is 6mm is 42.455 Mpa and since it’s greater than 40 Mpa, fracture occurs to the material