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

4. Downward and its value is constant

Step-by-step 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-(1)/(2) gt^(2)`

Where
`v_(0)`, is the initial velocity.