Download Phy 2053 Course Announcements and Problems and more Assignments Physics in PDF only on Docsity! 1 Phy 2053 Announcements Homework 1 due Jan 21 is posted in webassign. It will count towards course grade. 3 more days to register your code in webassign Yellow book (past exams and solutions) available at Target Copy for $16 Should have received email listing your clicker response. Clicker questions will count towards course grade starting Jan 27. Optional solution manual: a limited number of copies will be available today at the UF bookstore, at ~ $54. It contains solutions to some but not all of the problems at the back of chapters. Kinematic Equations Used in situations with uniform acceleration = +ov v at 2 o at2 1tvx +=∆ = + ∆2 2 2ov v a x (1) (2) (3) t 2 vvtvx foaverage ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +==∆ Important: use the correct sign for x, v and a. Some examples of Use t 2 vvtvx foaverage ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +==∆Acceleration not in equation = + ∆2 2 2ov v a xTime not in equation : = +ov v atDisplacement not in equation: 2 o at2 1tvx +=∆Final velocity not in equation : Free Fall If only force on object moving near surface of the earth is gravity it is in free fall Free fall is constant acceleration (same for all objects) The acceleration is called the acceleration due to gravity, symbolized by g g = 9.80 m/s² When estimating, use g ≈ 10 m/s2 g is always directed downward toward the center of the earth Ignore air resistance and assume g doesn’t vary with altitude over short vertical distances Forces can apply to the object before or after the free fall Free Fall options • Initial velocity is zero • Throw down –initial velocity is negative • Starting and ending heights may be equal – symmetric or not equal-asymmetric - trajectory v = 0 • Throw up -initial velocity non-zero and positive— instantaneous velocity at maximum height = 0 2-53. A model rocket is launched straight upward with an initial speed of 50.0 m/s. It accelerates with a constant upward acceleration of 2.00 m/s2 until its engines stop at an altitude of 150 m. (a) what can you say about the motion of the rocket after its engines stop? (b) What is the maximum height reached by the rocket? (c) How long after lift-off does the rocket reach its maximum height? (d) How long is the rocket in the air? A Typical Problem 2 Vectors in one dimension: positive or negative, and magnitude Vectors in two dimensions: direction and magnitude Vectors Equality of Two Vectors Two vectors are equal if they have the same magnitude and the same direction A v B v C v D v BA vv = CA vv ≠ DA vv ≠ Graphically Adding Vectors When you add vectors, just put the tail of one on the head on the next… The resultant is drawn from the origin of the first vector to the end of the last vector. R ur The order in which the vectors are added doesn’t affect the result R ur + = +A B B A r r r r Commutative law of addition Scalar Multiplication The result of the multiplication or division of a vector by a scalar is a vector-the magnitude of the vector is multiplied or divided by the scalar •If the scalar is positive, the direction of the result is the same as of the original vector •If the scalar is negative, the direction of the result is opposite that of the original vector A v 2 1 A v 2−A v Vector Subtraction Special case of vector addition--add the negative of the subtracted vector Continue with standard vector addition procedure ( )− = + −A B A Br r r r Vector Components The x-component of a vector is the projection along the x-axis cosA A θ=x x θ= uur ur cosAA x The y-component of a vector is the projection along the y-axis sinyA A θ= y θ= uur ur sinAA y These equations are valid only if θ is measured with respect to the x-axis x y= + r r r A A AThen,
