If the acceleration due to gravity on the Moon is 1/6 that what is on the Earth, what would a 100 kg man weight on the Moon? If a person tried to simulate this gravity in an elevator, how fast would it have to accelerate and in which direction?
The acceleration due to gravity on the moon is
The weight of a 100-kg man on the moon is
If the elevator is accelerating upward then the acceleration would be greater. The person would be pushed toward the ﬂoor of the elevator making the weight increase. Therefore, the elevator must be going down to decrease the acceleration.
For a 100 kg man to experience a 163.3 N in an elevator,
Therefore, the elevator should be accelerated at 8.167 m/s2 downward for a 100-kg man to simulate his weight just like his weight in the moon which has 1/6 of the Earth’s gravity acceleration.
A not so brilliant physics student wants to jump from a 3rd-floor apartment window to the swimming pool below. The problem is the base of the apartment is 8.00 meters from the pool’s edge. If the window is 20.0 meters high, how fast does the student have to be running horizontally to make it to the pool’s edge?
Since the student will be running horizontally, there is no initial vertical velocity, . We are also given , and .
Consider the vertical component of the motion.
Consider the horizontal component of the motion
Therefore, the student should be running 3.96 m/s horizontally to make it to the pool’s edge.
A ship has a top speed of 3 m/s in calm water. The current of the ocean tends to push the boat at 2 m/s on a bearing of due South. What will be the net velocity of the ship if the captain points his ship on a bearing of 55° North of West and applies full power?
The x component of the resultant is negative and the y component is positive, thus the resultant is located at the second quadrant.
Therefore, the magnitude of the net velocity of the ship is 1.78 m/s, and is going 14.9 degrees North of West
Explain a possible situation where you start with a positive velocity that decreases to a negative increasing velocity while there is a constant negative acceleration.
An example of this situation is a free-fall. If an object is thrown upward, the initial velocity is positive. Then the velocity decreases until the object thrown will reach its maximum height and then it goes back with a negative increasing velocity. In this entire flight, the acceleration is a constant negative–the acceleration due to the Earth’s gravity.
A car travels 120 meters in one direction in 20 seconds. Then the car returns ¾ of the way back in 10 seconds. Calculate the average speed of the car for the first part of the trip. Find the average velocity of the car.
The average speed of the car for the first part of the trip is