 Phyllis Fleming Physics Physics 104
 Review - One Dimensional Motion
 1 A fast sprinter can cover 100 m in 10 s flat. (a) What is the average speed of the sprinter? (b) What would his time be for the mile (1610 m) if he could keep up the sprint pace?
 2 If y = kx, where k is a constant, what is the effect on y: of (a) doubling x, (b) of halving x? (c) What does a graph of y as a function of x look like?
 3 If y = kx2, where k is a constant, what is the effect on y: of (a) doubling x, (b) of halving x? (c) What does a graph of y as a function: of (i) x and (ii) x2 look like?
 4 An object moves with a constant velocity of 15 m/s. (a) How far will it travel in 2.0 s? (b) If the time is doubled, how far will it travel?
 5 An object, initially at rest, moves with a constant acceleration of 10 m/s2. How far will it travel in (a) 2.0 s and (b) 4.0 s? If this object had an initial velocity of 4 m/s, how far will it travel in (c) 2.0 s and (d) 4.0 s?
 6 (a) An object moving with constant acceleration changes its speed from 20 m/s to 60 m/s in 2.0 s. What is the acceleration? (b) How far did it move in this time?
 7 The speed of light is 3.0 x 108 m/s. Assume that the length of a "standard room" is 20 m (22 yards). How many "room lengths" can light travel in 20/3 s?
 8 A pitcher throws a baseball with a velocity of 132 ft/s (90 mph) toward home plate that is approximately 60 ft away. Assuming the horizontal velocity of the ball remains constant, how long does it take to reach the plate?
 9 An object moving with constant acceleration along a horizontal path covers the distance between two points 60 m apart in 6.0 s. Its speed as it passes the second point is 15 m/s. Find (a) the speed at the first point, (b) its acceleration and (c) the initial distance from the first point when the object was at rest.
 10 Figure 1 is a plot of the displacement x of an object as a function of time t. The dashed vertical lines separate the one-second intervals. During the first time interval (#1 or t = 0 to t = 1 s) of Fig. 1 decide if the velocity of the object is (a) zero (b) constant and positive, (c) constant and negative, (d) increasing and positive, (e) increasing and negative, (f) decreasing and positive, or (g) decreasing and negative. (You may use a ruler to check the slopes of x vs t for the various time intervals.) Also decide for the same intervals if the acceleration is (note do not fix on one point in an interval) (h) positive (i) negative (j) zero. Explain your answers. Repeat the above for the other four time intervals in Fig. 1. 11 A car is traveling along a straight level road at a speed of 80 ft/s (54.5 mph). The brakes of the car are capable of producing a negative acceleration of -20 ft/s2. (a) How long will it take the car to stop? (b) How far will the car travel in this time? (c) Now assume that it takes one and one-half second for the driver of the car to become aware of the need to stop and another half-second before her brakes take hold. How far will the car travel before it comes to a stop if we assume, as before that she was initially traveling with a speed of 80 ft/s? (d) If we take 15 ft as the length of the car, how many "car lengths" will the car travel in (c) before coming to a halt?
 12 In Fig. 2 at t = 1.0 s, the velocity of the particle is +15 m/s. At t = 5.0 s, the velocity of the particle is -15 m/s. Are (a) the magnitudes of the velocity at these two times equal? (b) The directions of the velocity at these two-time the same?
 13 Figure 2 shows the velocity of a particle as a function of time. (a) Find the acceleration for the five one-second periods and plot the acceleration as a function of time. (b) Taking x = 0 at t = 0, find the position of the particle at t = 0.5 s, t = 1.0 s, t = 2.0 s, t = 3.0 s, t = 4.0 s, and t = 5.0 s and plot the position as a function of time. Look at the slopes of your x vs t curve for the five one-second periods and show that they correspond to the velocities of Fig. 2. 14 A ball thrown straight up takes 2.0 s to reach a height of 40 m. Find (a) Its initial speed, (b) its speed at this height, and (c) how much higher the ball will go. Take g = 10 m/s2.
 15 A ball is thrown down vertically with an initial speed of 20 m/s from a height of 60 m. Find (a) its speed just before it strikes the ground and (b) how long it takes for the ball to reach the ground. Repeat (a) and (b) for the ball thrown directly up from the same height and with the same initial speed. Take g = 10 m/s2.
 16 An object moving with a velocity of 10 m/s is uniformly decelerated, coming to rest in a distance of 20 m. Find (a) its deceleration and (b) the time for it to come to rest. Plot (c) its velocity v as a function of time t and (d) its position x as a function of t. Take xo = 10 m.
 17 An apartment dweller sees a flowerpot (originally on a windowsill above) pass the 2.0-m-high window of her fifth floor apartment in 0.10 s. The distance between floors is 4.0 m. From which floor did the pot fall?
 18 At a certain instant, a ball is thrown downward with a velocity of 8.0 m/s from a height of 40 m. At the same instant, another ball is thrown upward from ground level directly in line with the first ball with a velocity of 12 m/s. Find (a) the time when the balls collide, (b) the height at which they collide and (c) the direction the second ball is traveling when they collide. Take g = 10 m/s2.
 19 Sketch a graph that is a possible description of position as a function of time for a particle that moves along the x axis and, at t = 1 s, has (a) zero velocity and positive acceleration; (b) zero velocity and negative acceleration; (c) negative velocity and positive acceleration; (d) negative velocity and negative acceleration. (e) For which of these situations is the speed of the particle increasing at t = 1 s?

 Homepage Sitemap
 Website Designed By: Questions, Comments To: Date Created: Date Last Updated: Susan D. Kunk Phyllis J. Fleming September 25, 2002 April 1, 2003