If the coefficient of kinetic friction between tires and dry pavement is 0.75, what is the shortest distance in which you can stop an automobile by locking the brakes when traveling at 25.5 m/s ?
In: Physics
A projectile is launched with an initial speed of 40.0 m/s at 60.0 degrees above the horizontal. It hits the ground at the same height it was launched from. Neglect air resistance.
a) What is the projectile's smallest speed as it moves through air?
b) What is the projectile's smallest magnitude of acceleration as it moves through air?
c) What is the projectile's speed 1.00 second after launch?
d) What is the magnitude of the projectile's displacement 1.00 second after launch?
In: Physics
|
Two ice skaters, Daniel (mass 65.0 kg ) and Rebecca (mass 45.0 kg ), are practicing. Daniel stops to tie his shoelace and, while at rest, is struck by Rebecca, who is moving at 14.0 m/s before she collides with him. After the collision, Rebecca has a velocity of magnitude 8.00 m/s at an angle of 53.1 ∘ from her initial direction. Both skaters move on the frictionless, horizontal surface of the rink. |
Part A What is the magnitude of Daniel's velocity after the collision?
SubmitMy AnswersGive Up Part B What is the direction of Daniel's velocity after the collision?
SubmitMy AnswersGive Up Part C What is the change in total kinetic energy of the two skaters as a result of the collision? |
In: Physics
Why is it hard to measure the phenomenon experienced at the speed of light?
In: Physics
An electron that has an energy of approximately 3.0e+02 eV moves between rigid walls 0.6 nm apart.
(a) Find the quantum number n for the energy state that
the electron occupies.
_____________
(b) Find the precise energy of the electron.
_____________eV
In: Physics
a.)A 9 m ladder whose weight is 417 N is placed against a smooth vertical wall. A person whose weight is 846 N stands on the ladder a distance 3.4 m up the ladder. The foot of the ladder rests on the floor 1.98 m from the wall. Calculate the force exerted by the wall. Answer in units of N.
b.)Calculate the notmal force exerted by the wall. Answer in units of N.
In: Physics
Some people are able to spin a basketball on the tip of a finger. It is often done by balancing the ball on the tip of the finger and brushing the other hand along the side of the ball to cause it to rotate. Suppose the ball begins from rest and reaches a final angular speed of 20.15 rad/s in 1.55 s.
(a) Assuming the ball is subject to a constant angular acceleration, what is the magnitude of the constant angular acceleration? rad/s2
(b) Through how many revolutions does the ball rotate during the 1.55 s?
In: Physics
coil has 30 turns and carries current. The cross sectional area of the coil is 7.5cm. At a point located on the axis of the coil at a distance 1.5m, the magnetic field os 0.2mG, what is current in the coil?
In: Physics
When the tail light of a car is turned on, 0.5 A flows through the wires. The length of one wire from the battery to the tail light is 5.0 meters.Estimate how long you think it will take an electron to travel from the battery to the tail light and how many electrons flow through the tail in one minute. Thank you!
Given :
14AWG copper wire is used, which has a cross sectional area of 2.1e-6 m^2
2 The density of copper is 8.96 grams/cm^3
3 The atomic mass of copper is 63.5.
Each copper atom has one free electron.
(should be 3.3 days and 1.9e20 electrons per minute. How? ) Please show each steps. Thank you so much!
In: Physics
A 2.8kg balloon is filled with helium ( density = 0.179 kg/m 3 ).
Part A
If the balloon is a sphere with a radius of 5.1m , what is the maximum weight it can lift? (N)
In: Physics
A spring contains a weight of 32 lbs. It is stretched to a
distance of 1.6 ft and is
currently at rest. The damping force is 9 ˙x and an external force
of 2 cos 4t
applied. Set up the differential equation,
including the initial conditions, but
you do not need to solve.
In: Physics
At 3:00 the hour hand and the minute hand of a clock point in directions that are 90° apart. What is the first time after 3:00 that the angle between the two hands has decreased to 26.0°?
In: Physics
1. A 4 kg mass is resting on a ramp inclined at an angle of 30 degrees with respect to the horizontal. A string is attached to the 4 kg mass and passes over a frictionless pulley and is connected to a 5 kg mass hanging over the side. If the coefficient of friction between the ramp and the 4 kg mass if 0.3 find; A) The acceleration of both masses B) The tension in the string C) Find the speed of both blocks after they move a distance of 2 meters.
In: Physics
A mass of 11.0 kg , fastened to the end of an aluminum wire with an unstretched length of 0.47 m , is whirled in a vertical circle with a constant angular speed of 118 rev/min . The cross-sectional area of the wire is 2.0×10−2 cm2 .
Part A:
Calculate the elongation of the wire when the mass is at the lowest point of the path.
Express your answer using two significant figures.
Part B:
Calculate the elongation of the wire when the mass is at the highest point of its path.
Express your answer using two significant figures.
In: Physics