Category Archives: Sciences
Arizona State University| PHY 121: Univ Physics I: Mechanics|Homework 1-1| Problem 2
Learning Goal:
To subtract B⃗ from A⃗ (Figure 1), perform these steps:
- Draw A⃗ .
- Draw −B⃗ and place its tail at the tip of A⃗ .
- Draw an arrow from the tail of A⃗ to the tip of −B⃗ . This is vector A⃗ −B⃗ .
Arizona State University| PHY 121: Univ Physics I: Mechanics|Homework 1-1| Problem 1
To practice Tactics Box 1.1 Vector Addition.
- Draw A⃗ .
- Place the tail of B⃗ at the tip of A⃗ .
- Draw an arrow from the tail of A⃗ to the tip of B⃗ . This is vector A⃗ +B⃗ .
Grantham PHY220 Week 2 Assignment Problem 8
If a car is traveling at 50 m/s and then stops over 300 meters (while sliding), what is the coefficient of kinetic friction between the tires of the car and the road?
SOLUTION:
Draw the free-body diagram of the car
Consider the vertical direction
Consider the motion in the horizontal direction
Solve for the acceleration of the car.
Solve for the coefficient of kinetic friction
Grantham PHY220 Week 2 Assignment Problem 7
A 7.93 kg box is pulled along a horizontal surface by a force of 84.0 N applied at a angle. If the coefficient of kinetic friction is 0.35, what is the acceleration of the box?
SOLUTION:
The free-body diagram of the box
Solve for the normal force
Solve for the friction force
Solve for the acceleration in the horizontal direction
Therefore, the acceleration of the box is 6.51 m/s2 along the horizontal surface.
Grantham PHY220 Week 2 Assignment Problem 6
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?
SOLUTION:
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.
Grantham PHY220 Week 2 Assignment Problem 5
If a 1500 kg car stopped from an in 5.6 seconds with an applied force of 5000 N, how fast was it initially traveling?
Solution:
There is a negative acceleration since the car decelerates.
The car was initially traveling at .
Grantham PHY220 Week 2 Assignment Problem 4
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?
Solution:
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.
Grantham PHY220 Week 2 Problem 3
A bullet is fired from a gun at a shooting range. The bullet hits the ground after 0.32 seconds. How far did it travel horizontally and vertically in this time if it was fired at a velocity of 1100 m/s?
Solution:
Grantham PHY220 Week 2 Problem 2
An airplane is 5,000 m above an observer and 2.1 km to the west of them and 1.5 km to the north of you. Determine the angle to the plane in the x – y axis and the total distance to the plane from you. Choose the x-axis east, y axis north, and z axis up.
Solution:
The angle of the plane in the x-y axis
Solve for
The angle is 35.5 degrees measured from the west axis. If it is measured from the East axis, the angle would be 180-35.5=144.5 degrees.
The distance from the plane to the observer
Solve for
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