Answer:
Answer B is the correct answer: "<em>Motion of one projectile as seen from the other is a straight line.</em>"
Explanation:
Let's write the equations of motion for each projectile, using that projectile 
is launched with velocity which has components associated with the angle of launching, given in x and y coordinates as: 
.
Similarly, assume that projectile b is launched with velocity 
with components due to the launching angle = 
then the equations of motion for the two projectiles launched at the same time (t) from the same spot (position that we assume to be at the origin of coordinates to simplify formulas) are:
therefore, from the frame of reference of projectile "b", the x and y position of projectile "" would be:
which is linear in "t"
![y_{a\,\,b}=y_a-y_b= a_y\,t-\frac{1}{2} g\,t^2-\left[ b_y\,t-\frac{1}{2} g\,t^2\right]=(a_y-b_y)\,t](https://tex.z-dn.net/?f=y_%7Ba%5C%2C%5C%2Cb%7D%3Dy_a-y_b%3D%20a_y%5C%2Ct-%5Cfrac%7B1%7D%7B2%7D%20g%5C%2Ct%5E2-%5Cleft%5B%20b_y%5C%2Ct-%5Cfrac%7B1%7D%7B2%7D%20g%5C%2Ct%5E2%5Cright%5D%3D%28a_y-b_y%29%5C%2Ct)
which is also linear in t.
Therefore the motion of one projectile with reference to the other is a straight line (answer B)
Notice as well that this two projectiles cannot collide because they have been launched together, and supposedly at different speeds and angles. The only way that they can share the same x-coordinate and the same y-coordinate at the same time "t" is if their velocity components are equal, which is not what we are told.
Answer:
A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
Answer: k = 5.4kg/m
where m is the mass of the crate.
Explanation:
The force of kinetic friction is described by the equation:
Ff = k*N
in the opposite direction in wich the object moves, where k is the coefficient of kinetic friction and N is the normal force, that is equal to the weight of the crate. N = m*g where m is the mass of the crate and g is the gravitational acceleration.
If the crate keeps moving with constant velocity, this means that the crate is not accelerating so there is no net force applied on the crate. Then the friction force should be equal in magnitude to the horizontal force of 53N (but with different sign)
then we have:
k*m*g = 53N
k*m = 53N/9.8m/s^2 = 5.4kg
k = 5.4kg/m
In the question we do not have the mass of the crate, so you must put the value in that equation to get the value of k.
The answer to the question is
<span>PE = W = 1/2 (kx^2)
16.2 = </span>1/2 (k(0.30)^2)
k = 360 J/m^2
Answer:
60 m
Explanation:
After 3 seconds of travel at 20 m/s, the projectile is 3·20 = 60 meters horizontally from the cannon.
__
The vertical height after 3 seconds is 0.9 m, so the straight-line distance from cannon to target is √(60^2 +0.9^2) ≈ 60.007 meters.
