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: S2P6
The electronic configuraiton of given elements are as follows:
Ne =<span><span><span>[<span>He</span><span>]2</span></span><span>s2 2</span><span>p6<span>
</span></span></span>Ar = </span><span><span><span>[<span>Ne</span><span>]3</span></span><span>s2 3</span><span>p6<span>
</span></span></span>Kr = </span><span><span>[<span>Ar</span><span>]4</span></span><span>s2 3</span><span>d10 4</span>p6</span>
As it can be seen that for all three elements, their outermost orbital are completely filled, that is it has both s orbital, p orbital and d orbital fulfilled. Noble or inert gas atoms like Neon, Argon, Krypton have fulfilled valence shell. Fulfilled outermost orbital is the most stable electronic state, hence all elements tends to achieve such stability. These noble gas elements are called inert gas because of their fulfilled outermost shell. This means they don't react easily or take part in eletron donating, receiving or sharing. This is because, for all other elements except inert gas atoms, their valence shell is incomplete and they tend to react by other atoms so as to complete their outermost shell , which we call as duplet (in case of Helium like) or Octet state. Such elements either donate some electrons or receive some to acheive such stable state..
1 and 4 are tire.
2 and 3 are not.
Answer:
the cannonball’s velocity parallel to the ground is 86.6m/S
Explanation:
Hello! To solve this problem remember that in a parabolic movement the horizontal component X of the velocity of the cannonball is constant while the vertical one varies with constant acceleration.
For this case we must draw the velocity triangle and find the component in X(see atached image).
V= Initial velocity=100M/S

V= Initial velocity=100M/S
Vx=cannonball’s velocity parallel to the ground
Solving for Vx
Vx=Vcos30
Vx=(100m/S)(cos30)=86.6m/s
the cannonball’s velocity parallel to the ground is 86.6m/S
Answer:
“We have a brain for one reason and one reason only, and that's to produce adaptable and complex movements,” stated Wolpert, Director of the Computational and Biological Learning Lab at the University of Cambridge. ... The evidence for this is in how well we've learned to mimic our movements using computers and robots.