Answer:
He needs 1.53 seconds to stop the car.
Explanation:
Let the mass of the car is 1500 kg
Speed of the car, v = 20.5 m/s
He will not push the car with a force greater than, 
The impulse delivered to the object is given by the change in momentum as :

So, he needs 1.53 seconds to stop the car. Hence, this is the required solution.
Answer:
I think it is H2O . Formula of water
Answer:
The shear modulus of the polymer is 5 MPa
Solution:
As per the question:
displacement of the top plate, d = 2 mm = 0.002 m
Horizontal Force, P = 2 kN = 2000 N
Width of the block, w = 100 mm = 0.1 m
By small angle analysis:
Angle, 
Now,
Stress,
= 

25mph I hope this helps and sorry it took so long
Last month, we featured IRB best practices (“IRBs: Navigating the Maze” November 2007 Observer), and got the ball rolling with strategies and tips that psychological scientists have found to work. Here, we continue the dissemination effort with the second of three articles by researchers who share their experiences with getting their research through IRB hoops. Jerry Burger from Santa Clara University managed to do the seemingly impossible — he conducted a partial replication of the infamous Milgram experiment. Read on for valuable advice, and look for similar coverage in upcoming Observers. These are the first words I said to Muriel Pearson, producer for ABC News’ Primetime, when she approached me with the idea of replicating Stanley Milgram’s famous obedience studies. Milgram’s work was conducted in the early 1960s before the current system of professional guidelines and IRBs was in place. It is often held up as the prototypic example of why we need policies to protect the welfare of research participants. Milgram’s participants were placed in an emotionally excruciating situation in which an experimenter instructed them to continue administering electric shocks to another individual despite hearing that person’s agonizing screams of protest. The studies ignited a debate about the ethical treatment of participants. And the research became, as I often told my students, the study that can never be replicated. Hope this helps!