Question

A dart gun shoots a dart with an angle of 45' above horizontal During the upward part of the trajectory the gravitational acceleration g is directed 1 Upward and ts value changes with height 2 Upward and its value changes with height 3 There is no accelaration 4 Downward and its value is constant 5 Downward and ts value changes with height

Answer 1

Answer:

4. Downward and its value is constant

Explanation:

As this is a case of projectile motion, we use the reference frame where upward direction to be positive for $y$, and in the same way to be negative in the downward direction. On another hand, we have that gravity is always acting this means that gravitational acceleration g is directed downward constantly over the dart not only during the upward but also during the downward part of the trajectory. And it is ruled by the following equations.

For the x-axis

$v_{x}=v_{0}cos(45\°)=constant$

$x=(v_{0}cos(45\°))t$

For the y-axis

$v_{y}=v_{0}sin(45\°)-gt$

$y=v_{0}sin(45\°)t-\frac{1}{2} gt^{2}$

Where $v_{0}$, is the initial velocity.