What must be true if an object is speeding up in a straight line? The x component of the acceleration must be negative. The direction of the acceleration is the same as the direction of the velocity. O The acceleration is perpendicular to the velocity. O The direction of the acceleration is opposite the direction of the velocity. O The x component of the acceleration must be positive.

What must be true if an object is speeding up in a straight line? The x component of the acceleration must be negative. The direction of the acceleration is the same as the direction of the velocity. O The acceleration is perpendicular to the velocity. O The direction of the acceleration is opposite the direction of the velocity. O The x component of the acceleration must be positive.

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter2: Motion In One Dimension

Section: Chapter Questions

Problem 30P: A speedboat increases its speed uniformly from vi = 20.0 m/s to Vf = 30.0 m/s in a distance of 2.00 ...

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A speedboat increases its speed uniformly from vi = 20.0 m/s to Vf = 30.0 m/s in a distance of 2.00 102 m. (a) Draw a coordinate system for this situation and label the relevant quantities, including vectors, (b) For the given information, what single equation is most appropriate for finding the acceleration? (c) Solve the equation selected in part (b) symbolically for the boats acceleration in terms of vf, vi, and x. (d) Substitute given values, obtaining that acceleration, (e) Find the time it takes the boat to travel the given distance.
A If the vector components of a particles position moving in the xy plane as a function of time are x=bt2i and y=ct3j, where b and c are positive constants with the appropriate dimensions such that the components will be in meters, at what time t is the angle between the particles velocity and the x axis equal to 45?
Which statements are NOT VALID for a projectile? Take upward as positive. The acceleration of the projectile is positive and decreasing when the projectile is moving upwards, zero at the top. and increasingly negative as the projectile descends. OThe projectile has the same x velocity at any point on its path. O The acceleration of the projectile is a constant negative value. The y component of the velocity of the projectile is zero at the highest point of the projectile's path.
You stand at the edge of a 22.0 m high cliff and throw a stone straight down with a speed of 8.00 m/s. Before it hits the ground, the stone is traveling with a speed of 22.3 m/s. Let down be the positive vertical direction. Using the given coordinate system, what is the sign of the displacement of the stone from the point it is released until just before it hits the ground? O Negative Zero O Positive
A basketball player throws a basketball into the air and watches as it undergoes projectile motion. What can we say about the acceleration of the ball while it is in the air? The acceleration is zero in every direction. The acceleration is zero in the x-direction and -9.8 m/s? in the y-direction. O The acceleration is -9.8 m/s2 in every direction. O The acceleration is -9.8 m/s2 in the x-direction and 0 in the y-direction.
1. A skydiver is falling straight down, along the negative y direction. o During the initial part of the fall, her speed increases from 16 to 28 m/s in 1.5 s. o Later, her parachute opens, and her speed decreases from 48 to 26 m/s in 11 s. o In both instances, determine the magnitude and direction of her average acceleration. 2. A projectile is launched from and returns to ground level. Air resistance is absent. The horizontal range of the projectile is measured to be R = 175 m, and the horizontal component of the launch velocity is Vox = 25 m/s. Find the vertical component Voy of the launch velocity. 3. When chasing a hare along a flat stretch of ground, a greyhound leaps into the air at a speed of 10.0 m/s, at an angle of 31.0 degrees above the horizontal. o What is the range of his leap and o For how much time is he in the air?
Which of the following statements INCORRECTLY describes the horizontal motion of a projectile? O The horizontal motion has non-zero acceleration. O The graph of its horizontal velocity as a funtion of time is a horizontal line. O The horizontal velocity is constant. O The graph of its horizontal position as a function of time is a straight line with non-zero slope. < Previous
Donald, a parachute jumper, is falling straight down towards a target on the ground at a constant speed of 12 m/s (note: the parachute is currently open --- this is not free-fall). When he is 2.0 km above his target, a sudden wind starts up, blowing 5.0 m/s due east. Assume that Donald continues to fall straight down at 12 m/s relative to the air, but not necessarily relative to the ground. a. Determine Donald's velocity (both magnitude and direction) relative to the ground. b. Assuming that the wind remains constant until Donald reaches the ground, how far away from the target does he land?
A cross-country runner has a speed of 3.30 m/s and runs in a direction 20.0° counterclockwise from the positive x-axis. (a) What are the components of the runner's velocity, in meters per second? x component y component m/s m/s (b) If the runner slows down until his speed is one quarter of the original speed, how will it affect the components of his velocity? O His velocity components will be quartered. O His velocity components will be quadrupled. O His velocity components will not change. O His velocity components will be halved.
5. A car starts from Jeddah goes 50 km in a straight line to Makah, immediately turns around and returns to Jeddah, The time for this roundtrip is 2 hours. The magnitude of the average velocity of the car for this round trip is O km/h 100 km/h 50 km/h 200 km/h A в D 6. of the following situations, which one is impossible? A body having velocity east and acceleration east A body having velocity east and acceleration west A body having variable velocity and constant acceleration A body having constant velocity and variable acceleration. A B D 7. A particle moves along the x axis according to the equation x=6t, where x is in meter and t is in second, the speed of the particie is: 2 m/s 6 m/s 4 m/s 12 m/s A B D
A football is punted from the ground, it passes through the apex of its flight, and it begins its downward decent. When its height above the field is h=2.8m, the horizontal and vertical components of its velocity are observed to have the values vhorizontal=18m/s and vvertical=1.25m/s, respectively. a. Determine the magnitude of the horizontal component of the football’s initial velocity v0x�, in terms of vhorizontal, vvertical, g, and h. Write an expression for that equation using those variables. b. Calculate the time, in seconds, from when the football left the ground until it is descending at a height of h=2.8m It would be greatly appreciated if you can answer this because I really need help. Thank you.
What happens to the motion of an object that is thrown upward? O Neither its velocity nor its acceleration is zero. O Its velocity is not zero, but its acceleration is zero. O Both its velocity and acceleration are zero. O Its velocity is zero, but its acceleration is not zero.