physics ch.3 plr

Consider a particle with initial velocity that has magnitude 12.0 m/s and is directed 60.0 degrees above the negative x axis. What is the x component of v?

-6.00m/s

How long tg does it take for the balls to reach the ground? Use 10 m/s^2 for the magnitude of the acceleration due to gravity.

1.0s

Consider a particle with initial velocity that has magnitude 12.0 m/s and is directed 60.0 degrees above the negative x axis. What is the y component of v?

10.4m/s

Imagine that the ball on the left is given a nonzero initial velocity in the horizontal direction, while the ball on the right continues to fall with zero initial velocity. What horizontal speed vx must the ball on the left start with so that it hits the ground at the same position as the ball on the right?

3.0m/s

A football player kicks a football in a field goal attempt. When the football reaches its maximum height, what is the relationship between the direction of the velocity and acceleration vectors? Assume air resistance is negligible.

At the maximum height, the velocity and acceleration vectors are perpendicular to each other.

How does the vertical acceleration at point A compare to the vertical acceleration at point C?

Both accelerations are equal to free fall acceleration. The human cannonball is in free fall at all times. Thus, the vertical acceleration at point A and at point C is equal to free fall acceleration.

How does the magnitude of the horizontal velocity change as the human cannonball passes through points A, B, C, D, and E?

It does not change. Because there is no air resistance, no net horizontal force acts on the human cannonball. Thus, the horizontal velocity is constant.

At what angle, above the horizon, should a cannon be fired in order for the cannon ball to obtain the greatest horizontal range? Assume air resistance is negligible.

The cannon should be fired at an angle of 45° above the horizon.

For general projectile motion, which of the following best describes the horizontal component of a projectile's acceleration? Assume air resistance is negligible.

The horizontal component of a projectile's acceleration is zero.

For general projectile motion, which of the following best describes the horizontal component of a projectile's velocity? Assume air resistance is negligible.

The horizontal component of a projectile's velocity remains a nonzero constant.

For a projectile launched horizontally, which of the following best describes the horizontal component of a projectile's velocity? Assume air resistance is negligible

The horizontal component of the projectile's velocity remains a nonzero constant.

A pilot releases a package from a plane flying horizontally at a constant speed. When the package reaches the ground below, what is the horizontal location of the plane with respect to the package? Assume air resistance is negligible.

The plane will be located directly above the package.

A player kicks a soccer ball in a high arc toward the opponent's goal. When the soccer ball reaches its maximum height, how does its speed at this point compare to its initial speed? Assume air resistance is negligible.

The speed at its highest point is less than its initial speed.

A red water balloon is thrown horizontally from the top of a bridge. At the same instant, a yellow water balloon is dropped off the bridge from the same height. Compare the time of fall for the two balloons. Assume air resistance is negligible.

The two balloons hit the ground at the same time.

The motion diagram for a projectile is displayed, as are the motion diagrams for each component. The x component motion diagram is what you would get if you shined a spotlight down on the particle as it moved and recorded the motion of its shadow. Similarly, if you shined a spotlight to the left and recorded the particle's shadow, you would get the motion diagram for its y component. How would you describe the two motion diagrams for the components?

The vertical component exhibits motion with constant nonzero acceleration, whereas the horizontal component exhibits constant-velocity motion.

For general projectile motion, which of the following best describes the vertical component of a projectile's acceleration? Assume air resistance is negligible.

The vertical component of a projectile's acceleration remains a nonzero constant.

For a projectile launched horizontally, which of the following best describes the vertical component of a projectile's velocity? Assume air resistance is negligible.

The vertical component of the projectile's velocity continually increases.

When launched, the human cannonball's initial velocity has a positive x-component and a positive y-component. Rank the vertical velocity components at points A through E from most positive to most negative.

Treating the human cannonball as an ideal projectile means that it has a constant downward, or negative, acceleration. Thus, the initially positive y-component of velocity decreases until it reaches zero, then continues to become increasingly negative.

Is the vertical component of velocity ever zero? If so, where?

Yes, it is zero at point C. The constant downward acceleration due to gravity decreases the vertical component of velocity from its initial positive value to zero at the peak height.