Kinematics
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Obtain the equation for displacement as a function of time with constant velocity from the expression of instantaneous velocity.

Obtain the expression for displacement as a function of time with constant acceleration from the expression of instantaneous acceleration.

The speed of a body is given by
\[ \begin{gather} v=t^3-4t^2+2t+5 \end{gather} \]
a) What is the position of the body at t = 3 s, if initially it is at x = 6 m?
b) What is the acceleration of the body at t = 3 s?

A body moves with acceleration given by
\[ \begin{gather} a=\alpha-\beta v \end{gather} \]
α and β are real positive constants that make the expression dimensionally consistent. Determine the expressions for the velocity and displacement as a function of time.

Two bodies are in a straight line with constant acceleration on the same trajectory, their motions are described by the equations
\[ \begin{gather} \left. \begin{array}{l} x_1=2t-\dfrac{1}{2}t^2\\ x_2=10-3t+\dfrac{3}{2}t^2 \end{array} \right. \qquad\text{(S.I. units)} \end{gather} \]
Determine:
a) The position where they meet;
b) The instant of time that the distance between the two bodies is the smallest and the distance between them;
c) The instant of time in which the speeds of the bodies change direction and their positions.

A body moves with acceleration given by
\[ \begin{gather} a=\alpha x \end{gather} \]
where α is a positive real constant that makes the expression dimensionally consistent. The initial velocity of the body is equal to v0 at position x0. Determine the expression for velocity as a function of position.

A steamboat, sails at a constant speed v (km/h), and consumes 0.3 + 0.001v3 tonnes of coal per hour. Calculate:
a) The speed that should have a 1000 km route to have a minimum consumption;
b) The amount of coal consumed on this trip.

Two particles run perpendicular to each other trajectories that intersect at a common origin. The particles leave at the same time from points x0 and y0 toward the origin, both with the same constant acceleration in magnitude. Calculate:
a) After how long after they leave they will be at the smallest distance;
b) What is the smallest distance.

A particle is on a plane xy, initially at rest in the position x0 on the positive x-axis. It begins to move with constant velocities vx, in the direction of origin, and vy in the direction of the positive y-axis. Determine after how long the particle will be at the minimum distance of the origin and, what is this minimum distance.
Solution scalar

Solution using vectors

Solution using differentiation
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