There's no way to figure it out. It's your choice! Gravity is always directed towards the Earth - there is no choice about that.bluesteels said:Summary:: i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
Most textbooks would already insert the minus sign in the latter case, so you would still replace g with 9.8.anuttarasammyak said:If +y has same direction with gravity, it is 9.8.
If +y has opposite direction with gravity, it is -9.8.
Every rextbook does it differently. You would need to look at the relevant chapters and read some of the worked examples.bluesteels said:Summary:: i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
The sign of a value in a kinematic equation depends on the direction of the motion. If the object is moving in the positive direction, the value is positive. If the object is moving in the negative direction, the value is negative.
+g represents the acceleration due to gravity when an object is moving in the positive direction, while -g represents the acceleration due to gravity when an object is moving in the negative direction. The value of g is always positive, but the sign changes depending on the direction of motion.
The sign of y in a kinematic equation depends on the coordinate system being used. If the positive direction is defined as up, then +y will be used for any values related to vertical motion. If the positive direction is defined as down, then -y will be used for vertical motion.
If you use the wrong sign in a kinematic equation, it will result in an incorrect answer. The sign is important in determining the direction and magnitude of the motion, so using the wrong sign can lead to significant errors in calculations.
One way to keep track of the signs in kinematic equations is to draw a diagram or use a coordinate system to represent the direction of motion. Another way is to consistently use the same sign convention throughout all equations and calculations. It is also helpful to double-check the signs before plugging in values and solving the equation.