Module 3
A celebrating student throws a water balloon horizontally from a dormitory window that is 50 m above the ground. It hits the ground at a point 60 m from the building without appreciable air resistance. (a) What will be the horizontal component of the velocity of the balloon just before it hits the ground? (b) What will be the magnitude of the vertical velocity of the balloon just before it hits the ground?
(a) 19 m/s (b) -31 m/s
The driver of a motorboat that can move at 10 m/s in still water wishes to travel directly across a river in which the current flows at 5.0 m/s. (a) At what angle, measured from the upstream direction, should the driver head the boat? (b) How many minutes will it take to cross the river if it is 1.6 km wide at that point?
(a) 30° (b) 5.3 min
A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will
be directly over the package
If vectors A + B = C and their magnitudes are given by A + B = C, then the vectors A and B are oriented...
parallel to each other
Four vectors are shown in the figure. The sum of these four vectors is a vector having magnitude and direction
4.0 cm along the y-axis
A player throws a football 50.0 m at 61.0° north of west. What is the westward component of the displacement of the football?
24.2 m
Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just before the snowballs reach the ground below? (There could be more than one correct choice.) Debra's snowball will stay in the air longer than Mary's snowball. Mary's snowball will stay in the air longer than Debra's snowball. Both snowballs will take the same amount of time to hit the ground. Debra's snowball has exactly the same acceleration as Mary's snowball. Mary's snowball has a greater downward acceleration than Debra's snowball.
Debra's snowball will stay in the air longer than Mary's snowball. Debra's snowball has exactly the same acceleration as Mary's snowball.
A ball rolls over the edge of a platform with a horizontal velocity of magnitude v. The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m. What is the magnitude of v if air resistance is negligibly small?
The horizontal velocity of magnitude v is 35 m/s.
T or F: If three vectors add to zero, they must all have equal magnitudes.
false
T or F: A boulder rolls off of a very high cliff and experiences no significant air resistance. While it is falling, its trajectory is never truly vertical.
true
