Chapter 3

• Vectors and scalars are used in kinematics in two dimensions.
• The addition of vectors can be done graphically.
• Subtraction of vectors, and multiplication of a vector by a scalar, can be done graphically.
• Adding vectors by components is a method of solving projectile motion problems.
• Projectile motion is parabolic.
• Relative velocity is a concept in kinematics in two dimensions.
• Motion in two dimensions can be analyzed using Galileo's principle of relativity.
• Motion in two dimensions can also be analyzed using the principle of conservation of energy.
• The term velocity refers to both how fast an object is moving and its direction.
• The acceleration of gravity is 9.80 m/s^2.
• The snowflakes hit at the same time.
• The initial velocity of the box can be horizontal or down.
• The box provides the initial velocity of the box.
• The speed of the vertically falling snowflakes relative to the ground can be estimated by constructing a relative velocity diagram similar to Fig 3-29 or 3-30.
• The initial velocities and flight times (elapsed time from launch until landing) for A and B are different.
• The equation for the acceleration of an object is v = vx 0 = 16.0 m/s.
• Both A and B have the same level horizontal range.
• When driving south on a highway in a snowstorm, the snow is coming down vertically, but it is passing the windows of the moving car at an angle of 7.0° to the horizontal.
• A quantity such as velocity, which has direction as well as magnitude, is a vector quantity.
• Displacement, force, and momentum are other vector quantities.
• The kinematic equations for the x and y components of the motion in two-dimensional motion at constant acceleration are given by Eqs. 2 – 11a through 2 – 11c.
• The initial vertical velocity in projectile motion is zero.
• In projectile motion, the subscript 0 means “at t = 0”.
• In solving problems involving projectile motion, a time interval is considered for which the chosen object is in the air, influenced only by gravity.
• In projectile motion, the projection angle is chosen relative to the axis.
• The kinematic equations for the vertical and horizontal components of the motion in projectile motion are given by Eqs. 2 – 11a through 2 – 11c.
• In projectile motion, the initial velocity is horizontal and is the unknown.
• The acceleration due to gravity is denoted as g.
• Mass, time, and temperature are scalar quantities.
• The tail-to-tip method of adding vectors can be extended to three or more vectors.
• The resultant in the parallelogram method is the diagonal drawn from the common origin.
• The three vectors could represent displacements (northeast, south, west) or perhaps three forces.
• The difference between two vectors is defined as the sum of the first plus the negative of the second.
• The tail-to-tip method and the parallelogram method yield the same result.
• Our rules for addition of vectors can be applied using the tail-to-tip method.
• The resultant no matter in which order you add the three vectors.
• The resultant is the same regardless of the diagonal used in the parallelogram.
• Another way to add two vectors is the parallelogram method, which is fully equivalent to the tail-to-tip method.
• The resultant is drawn from the tail of the first vector to the tip of the last one added.
• In the parallelogram method, the two vectors are drawn starting from a common origin, and a parallelogram is constructed using these two vectors as adjacent sides.