Let's start with the concept of momentum. What is it? Linear momentum in physics is mathematically written as a product of mass and velocity of an object. Now let us suppose a body of mass m is moving in an inertial frame of reference with velocity v. Consider the fact that no external force is acting on the system. The momentum of this body is given by mv, where m is the mass and v is its velocity. In case of simple real world problems not delving into the realms of relativity, mass is a conserved quantity and it cannot be zero. Hence the velocity of the body must be zero and hence the momentum.
However, photons are considered to have a rest mass zero.
However note the point carefully "rest mass". A body in motion cannot have mass to be zero.
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Answer:
21 miles
Explanation:
3 miles an hour for 7 hours
Its simply 7m*3m/hr=21 miles
The values of t are <u>4.643 second</u> for the function 
What is batter misses?
An out in baseball happens when the umpire declares a batter or baserunner out. A hitter or runner who is out is no longer able to score runs and must go back to the dugout until their subsequent turn at bat. The batting team's turn is over after three outs are recorded in a half-inning.
In order to signal an out, umpires typically make a fist with one hand and then flex that arm, either upward on pop flies or forward on regular plays at first base. To indicate a called strikeout, home plate umpires frequently use a "punch-out" action.When a batter is struck by a pitched ball without making a swing at it, it is referred to as a hit-by-pitch. He consequently gets first base.
We have been given that
s = 6 feet
v = 73 feet per second
Substituting these values in the formula 

When the ball hits the ground, the height becomes zero. Thus, H(t)=0

We solve the equation using quadratic formula 
Substituting the values a=-16, b= 73, c=6

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the formula for momentum is velocity times mass
car :
1200 x 30 = 36000
truck:
2000 x 20 = 40000
Ans : truck has a greater momentum