A bullet is fired at 660 ms and strikes a target 200 m away. How long has it taken to hit the target?
Calculate the mass of a bus if it produces a force of 14,000 N while accelerating
at a rate of 5 ms 2 ?
You toss a ball at 30 ms' straight upward. How much time will the ball take
to reach the top of its path?
35​

Explanation:

The first question utilizes the one-dimensional equation

Δx = where Δx is the displacement of the bullet, v₀ is te initial velocity with which the bullet was fired, a is the acceleration in the horizontal dimension (which is always 0!), and t is the time in seconds. That's our unknown here. Filling in:

and

200.0 = 660t so

t = .30 seconds

The second question is a simple application of Newton's 2nd Law which says force = mass times acceleration:

14000 = m(5.0) so

2800 kg = m

The third question is a bit more interesting. We will use the one-dimensional equation

where v is the final velocity of the ball (which is always 0 at the top of its projectile path!), v₀ is the initial velocity of the ball, a is the pull of gravity on the ball, and t is the time it takes to do this. Filling in:

0 = 30 + (-9.8)t and

-30 = -9.8t so

t = 3.1 seconds

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.

small = small current large mag large current