Physics Work,Power & Energy Level: High School
Conservation of energy
A mass of 1.0 kg is pushed against a spring with a spring constant of 25 N/m . As a result , the spring is compressed by 20 cm . The mass is then released .What is the amount of potential energy acquired by the spring when it is compressed ?
a) 5.0 J
b) 0.20 J
c) 0.50 J
d) 10 J
Physics Work,Power & Energy Level: High School
An object of mass 20 kg is raised vertically through a distance of 8.0 m above ground level . Using g = 10 m/s squared what is the potential energy of this object at this position ?a) 160 N/m
b) 160 Nm
c) 1600 N/m
d) 1600 Nm
Physics Work,Power & Energy Level: Middle School
An object of mass 4.0 kg is moved from a point A to a point C as follows : 0.80 m vertically from A to B , and then 0.60 m horizontally from B to C . What is the amount of work done as the object is moved from point A to C ? Use g = 10 m/s squared .a) 1.3 J form A to B and 16 J from B to C .
b) 2.2 J from A to B and 32 J from B to C .
c) 32 J from A to B and 0 J from B to C .
d) 4.0 J from A to B and 16 J from B to C .
Physics Alternating Current Level: High School
Instantaneous Voltage
A time delay of 25 ms is required for the voltage to fall to 20 % of its maximum value . Rearrange the equation to find a new value of resistance to achieve this if the capacitance is kept the same .
Physics Alternating Current Level: High School
Instantaneous voltage
The instantaneous voltage in a capacitor circuit where v = Ve-t/cr . C is 2 microfarrad and f resistance R is 25 kilo ohms , V is 100 volts , and t is time , plot the function against time and from this find the voltage after 80 milliseconds . (Note : c and r is called time constant. ) After 5 CR the voltage will have settled . multiply 5 by C by R and plot to this time .
Physics Force & Laws Of Motion Level: High School
A vertical aerial AB, 9.60 m high stands on ground , which is inclined 12 degrees to the horizontal , a stay connects the top of the aerial A to a point C on the ground 10.0 m downhill from B , the foot of the aerial . Determine the length of the stay and the angle the stay makes with the ground .
Physics Force & Laws Of Motion Level: High School
Three forces acting on a fixed point are represented by the sides of a triangle of dimensions 7.2 cm , 9.6 cm and 11.0 cm , Determine the angles between the lines of action and the three forces .
Physics Magnetism,Magnetic Effects Of Current Level: High School
Force on a current carrying conductor in a magnetic field
A rail gun is a device that propels a projectile using a magnetic force . A simplified diagram of this device is shown above. The projectile in the picture is a bar of mass M and length D , which has a constant current I flowing through it in the +y direction as shown . The space between the thin frictionless rails contains a uniform magnetic field B , perpendicular to the plane of the page . The magnetic field and rails extend for a distance L . The magnetic field exerts a constant force F on the projectile as shown . Express all graphic answers to the following parts in terms of the magnitude F of the constant magnetic force , other quantities given above , and fundamental constants .
a) Determine the position x of the projectile as a function of time I while it is on the rail if the projectile starts from rest at x = 0 when t = 0 ,
b) Determine the speed of the projectile as it leaves the right-hand end of the track .
d) In what direction must the magnetic field B point in order to create the force F ? Explain your reasoning .
e) Calculate the speed of the bar when it reaches the end of the rail given the following value ?
B = 5 T , L = 10 m , I = 200 A , M = 0.5 kg , D = 10 cm
Physics Electromagnetic Induction Level: High School
A rectangular conducting loop of width w , height h , and resistance R is mounted vertically on a non conducting cart as shown in the figure at “click here” . The cart is placed on the inclined portion of a track and released from rest at position P1 at a height y0 above the horizontal portion of the track . It rolls with negligible friction down the incline and through a uniform magnetic field B in the region above the horizontal portion of the track . The conducting loop in the plane of the page and the magnetic field is directed into the page . The loop passes completely through the field with a negligible change in speed . Express your answer in terms of the given quantities and fundamental constants .a) Determine the speed of the cart when it reaches the horizontal portion of the track .
b) Determine the following for the time at which the cart is at position P2 ,with one-third of the loop in the magnetic field .
i) The magnitude of the emf induced in the conducting loop .
ii) The magnitude of the current induced in the conducting loop .
c) On the second diagram of the conducting loop , indicate the direction of the current when it is at position P2 ?
Question Diagram
Physics Ray Optics Level: High School
Polarization
Three polarizing disks whose planes are parallel are centered on a common axis . The directions of the transmission axes relative to the common vertical direction are shown . A linearly polarized beam of light with the plane of polarization parallel to the vertical reference direction is incident from the left on the first disk with intensity Ii = 1.89 units (arbitrary) . Calculate the transmitted intensity If when theta 1 = 17.4 degree , theta 2 = 38.2 degree , theta 3 = 77.8 degree .
Question Diagram
Mathematics Trigonometry Level: High School
Find all possible solution for the equation cos3x= (1/2)
Statistics Hypothesis Testing Level: University
In your own words explain the difference between a point estimate and an interval estimate of a parameter? Which is better? Why?
Physics Ray Optics Level: High School
Polarization
Three polarizing disks whose planes are parallel are centered on a common axis . The directions of the transmission axes relative to the common vertical direction are shown . A linearly polarized beam of light with the plane of polarization parallel to the vertical reference direction is incident from the left on the first disk with intensity Ii = 1.89 units (arbitrary) . Calculate the transmitted intensity If when theta 1 = 17.4 degree , theta 2 = 38.2 degree , theta 3 = 77.8 degree .Question Diagram
Physics Electromagnetic Waves Level: High School
The eye is most sensitive to light of wavelength 5.545 x 10^-7 m, which is in the green-yellow region of the visible electromagnetic spectrum . The speed of light is 3 x 10^8 m/s . What is the frequency of light ? Answer in units of Hz .Your answer must be within +-0.1% .
Physics Electromagnetic Waves Level: High School
Consider a beam of electromagnetic radiation , which is traveling along the positive z direction . Its average intensity is 316 W/m^2 . The permeability of free space is 1.257 x 10^-6 N/A^2 and the speed of light is 3 x 110^8 m/s . What is its maximum electric field ? Answer in units of N/C . What is the pressure on a surface which is perpendicular to the beam and is total reflective ? What is the maximum magnetic field ?Consider the electromagnetic wave pattern as shown in the figure at “click here†. The direction in which the wave is traveling is ?
a) from-right to left
b) from left-to-right
c) Undetermined ,since the figure shows a standing wave
Question Diagram
