Question

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​

Answer 1

Answer:

Explanation:

The first question utilizes the one-dimensional equation

Δx = $v_0t+\frac{1}{2}at^2$ 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:

$200.0=660t+\frac{1}{2}(0)t^2$ 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

$v=v_0+at$ 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