Classroom Examples for Test 1

Example #1
Hans stands at the rim of the Grand Canyon and yodels down to the bottom. He hears his yodel echo back from the canyon floor 5.20 s later. Assume that the speed of sound in air is 340.0 m/s. How deep is the canyon at this location?

Example #2
Two children cross a starting line at the same time, one running with a velocity of +3.5 m/s and the other with a velocity of -4.0 m/s. How far apart are they after 12 s?

Example #3
The brakes on your car can slow you at a rate of 5.2 m/s². If you are going 137 km/h and suddenly see a state trooper, what is the minimum time in which you can get your car under the 90 km/h speed limit? Start by sketching a position vs. time graph and a velocity vs. time graph.

Example #4
An airplane starts from rest and travels down a 401 meter runway. The airplane leaves the runway at 86 m/s.
a. Sketch a position vs. time graph.
b. Sketch a velocity vs. time graph.
c. Waht was the acceleration of the plane?

Example #5
In a bicycle race, the leader is traveling with a constant velocity of 11.1 m/s and is 10.0 m ahead of the second-place cyclist. The second-place cyclist has a velocity of +9.50 m/s and an acceleration of +1.20 m/s². How much time elapses before the second-place cyclist catches the leader?

Example #6
How long is Tina, a ballerina, in the air when she leaps straight up with a speed of 1.8 m/s?

Example #7
A stunt person sitting on a tree limb wishes to drop vertically onto a horse galloping under the tree. The constant speed of the horse is 10.0 m/s, and the man is initially 3.00 m above the level of the saddle. What must be the horizontal distance between the saddle and the limb when the man makes his move?

Example #8
A plane leaves an airport and flies 170 km at 68^o east of north and then changes direction to fly 230 km at 48^o south of east, after which it makes an immediate emergency landing in a pasture. When the airport sends out a rescue crew, in which direction and how far should this crew fly to go directly to this plane?

Example #9
With respect to the ground, Barbara is skating due south at a speed of 4.0 m/s. With respect to the ground, Neil is skating due west at a speed of 3.2 m/s. Find Neil’s velocity as seen by Barbara.

Example #10
A golf ball rolls off a horizontal cliff with an initial speed of 11.4 m/s. The ball falls a vertical distance of 15.5 m into a lake below. a) How much time does the ball spend in the air? b) What distance did the ball land from the base of the cliff?

Example #11
Superman is said to be able to “leap tall buildings in a single bound.” Suppose superman leaves the ground with a speed of 60.0 m/s at an angle of 75.0^o to the horizontal. a) How long is superman in the air? b) What is his horizontal range? c) What is his maximum height?

Example #12
A basketball player is standing 10.0 m from the basket. If he shoots the ball at a 40.0^o angle with the horizontal and it is released 2.00 meters above the ground, at what initial speed must he throw the basketball so that is goes through the hoop without striking the backboard? The height of the basket is 3.05 m.

Example #13
An electric vehicle starts from rest and accelerates at a rate of 2.0 m/s² in a straight line until it reaches a speed of 20.0 m/s. The vehicle then slows at a rate of 1.0 m/s² until it stops. a) How much time elapses from start to stop?b) How far does the vehicle travel from start to stop?

Example #14
A hot-air balloon is ascending at the rate of 12 m/s and is 80.0 m above the ground when a package is dropped over the side.a) How long does the package take to reach the ground?b) With what speed does it hit the ground?