How to find the initial velocity of the body
How to find the initial velocity of the body
Kinematics considers the changeThe spatial position of the bodies regardless of the causes that caused the movement. The body moves due to the forces acting on it, and this issue is the subject of study in dynamics. Kinematics and dynamics are the two main sections of mechanics.
Instructions
1
If the problem says that the body is movinguniformly, this means that the speed remains constant throughout the journey. The initial velocity of the body coincides with the velocity of the body in general, and the equation of motion has the form: x = x0 + v ∙ t, where x is the coordinate, x0 is the initial coordinate, v is the velocity, and t is the time.
2
Naturally, the movement is not alwaysuniform. A convenient case, often considered in mechanics, is the uniform motion of the body. Such conditions assume constant acceleration, both in modulus and in sign (positive or negative). Positive acceleration indicates that the speed of the body is increasing. With negative acceleration, the body gradually slows down.
3
When a material point moves with a constantThe acceleration is determined by the kinematic equation v = v0 + v0 ∙ t, where v0 is the initial velocity. Thus, the time dependence of the velocity will be linear. But the coordinate varies quadratically with time: x = x0 + v0 ∙ t + a ∙ t² / 2. By the way, the displacement is the difference between the final and initial coordinates.
4
A physical problem can be specifiedan arbitrary equation of motion. In any case, to find the velocity function from the coordinate function, it is necessary to differentiate the existing equation, because, by definition, the velocity is the first derivative of the time coordinate: v (t) = x '(t). To find the initial velocity from the velocity function, substitute t = 0 into the equation.
5
Sometimes you can find the acceleration of the body, applyinglaws of dynamics. Arrange all the forces acting on the body. Enter a pair of rectangular coordinate axes, relative to which you will consider the force vector. According to Newton's second law, the acceleration is directly proportional to the applied force and inversely proportional to the mass of the body: a = F / m. In another way, this is written as F = ma.
6
Actually, it is the force that determines howAccelerate the body. So, the traction force will cause the body to move faster, and the friction force will brake it. It is important to understand that in the absence of any external forces the body is able not only to be immobile, but also to move evenly in space. This is due to the inertial properties of the mass. Another question is that it is seldom possible to achieve conditions close to complete absence of forces.
