To understand the basic concepts of projectile motion. Projectile motion may seem rather complex at first. However, by breaking it down into components, you will find that it is really little different from the one-dimensional motions that you may already have studied. One of the most often used techniques in physics is to divide two- and three-dimensional quantities into components. For instance, in projectile motion, a particle has some initial velocity →v. In general, this velocity can point in any direction in the xy plane and can have any magnitude. To make a problem more manageable, it is common to break up such a quantity into its x component vx and its y component vy. Consider a particle with initial velocity → v that has magnitude 12.0 m/s and is directed 60.0degrees above the negative x axis. a) What is the x component vx of → v ? (Express your answer in meters per second.)
b) What is the y component vy of →v ? (Express your answer in meters per second.)

with 5 seconds, no, but over time if the police car stays at 65m/s ad the speeding car stays at 60, then obviously yes, but the answer to your question would be, no.

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in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

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im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.