Section 6 - Position-time graph and velocity
6.1 A fish swims north at 0.25 m/s for 3.0 seconds, stops for 2.0 seconds, and then swims south at 0.50 m/s for 4.0 seconds.
Draw a position-time graph of the fish's motion, using north as the positive direction.6.2 A renegade watermelon starts at x = 0 m and rolls at a constant velocity to x = í3.0 m at time t = 5.0 seconds. Then, it bumps
into a wall and stops. Draw its position versus time graph from t = 0 s to t = 10 s.Section 7 - Interactive problem: draw a position-time graph
7.1 Use the information given in the interactive problem in this section to answer the following questions. Assume that the
positive x direction is to the right. (a) Is the ball moving to the left or right from 0 s to 3.0 s? (b) Is the velocity from 3.0 s to
6.0 s positive, negative or zero? (c) What is a good strategy to match the graph from 7.0 s to 10.0 s? Test your answers using
the simulation.
(a) i. Left
ii. Right
iii. It is not moving
(b) i. Positive
ii. Negative
iii. Zero
(c) i. Start the ball moving slowly to the left and then increase its speed.
ii. Start the ball quickly moving to the left remaining at a constant speed.
iii. Start the ball slowly moving to the right and then increase its speed.
iv. Start the ball moving quickly to the right and then decrease its speed.Section 8 - Acceleration
8.1 The speed limit on a particular freeway is 28.0 m/s (about 101 km/hour). A car that is merging onto the freeway is capable of
accelerating at 2.25 m/s^2. If the car is currently traveling forward at 13.0 m/s, what is the shortest amount of time it could take
the vehicle to reach the speed limit?
s
8.2 A sailboat is moving across the water at 3.0 m/s. A gust of wind fills its sails and it accelerates at a constant 2.0 m/s^2. At the
same instant, a motorboat at rest starts its engines and accelerates at 4.0 m/s^2. After 3.0 seconds have elapsed, find the
velocity of (a) the sailboat, and (b) the motorboat.
(a) m/s
(b) m/sSection 9 - Average acceleration
9.1 A rail gun uses electromagnetic energy to accelerate objects quickly over a short distance. In an experiment, a 2.00 kg
projectile remains on the rails of the gun for only 2.10eí2 s, but in that time it goes from rest to a velocity of 4.00×10^3 m/s.
What is the average acceleration of the projectile?m/s^2
9.2 A baseball is moving at a speed of 40.0 m/s toward a baseball player, who swings his bat at it. The ball stays in contact with
the bat for 5.00×10í^4 seconds, then moves in essentially the opposite direction at a speed of 45.0 m/s. What is the magnitude
of the ball's average acceleration over the time of contact? (These figures are good estimates for a professional baseball
pitcher and batter.)
m/s^2
9.3 A space shuttle sits on the launch pad for 2.0 minutes, and then goes from rest to 4600 m/s in 8.0 minutes. Treat its motion
as straight-line motion. What is the average acceleration of the shuttle (a) during the first 2.0 minutes, (b) during the 8.0
minutes the shuttle moves, and (c) during the entire 10 minute period?
(a) m/s^2
(b) m/s^2
(c) m/s^2
9.4 A particle's initial velocity is í24.0 m/s. Its final velocity, 3.12 seconds later, is í14.0 m/s. What was its average acceleration?
m/s^2(^48) Copyright 2007 Kinetic Books Co. Chapter 2 Problems