Other Physics Answers

A speck of dust has a mass of 1.0 x 10-18 kg and carries a charge equal to that of one electron.

Near to the Earth's surface it experiences a uniform downward electric field of strength

100 N C-1 and a uniform gravitational field of strength 9.8 N kg-1.

Draw a free-body force diagram for the speck of dust. Label the forces clearly.

Calculate the magnitude and direction of the resultant force on the speck of dust.

Explain Atomic Excitation with detail.

Explain Nuclear Motion with details.

The position of a SHO as a function of time is given by x = 7.1cos 7πt  + π 

                          3      6

where t is in seconds and x is in centimetres. Find:

a)               the period and frequency expressed as fractions                        

b)              the velocity at t = 2.5 (to 2 sig. fig.)                                            

If a simple harmonic oscillator has velocity function of:

v                =      100πAsin(100πt – 0.75π)   Find:

         i) an expression for displacement, x.    

         ii) an expression for acceleration, a. 

A tuning fork is struck once and oscillates in simple harmonic motion at a

frequency of 642 Hz and the tip of each prong moves 2.5 mm to either side of

the centre.

i)                 Calculate the maximum velocity of one of the prong’s tip in mms^-1. [ANS = 10,085mms^-1] 

ii)              Find the maximum acceleration of one of the tip of the prongs in mms^-2.

[ANS =4.07 X 10⁷ mms^-2]

A small fly on mass 0.25 g is caught in a spider’s web. The web oscillates predominantly with a frequency of 4.0 Hz.

a)   What is the value of the effective spring stiffness constant k for the web? [ANS = 0.16 N m^-1]

b)  At what frequency would you expect the web to oscillate if an insect of mass 0.50 g were trapped? [ANS = 2.8 Hz]

Estimate the stiffness (k) of a spring in a child’s pogo stick if the child has a mass of 35 kg and bounces once every 2.0 seconds. [ANS = 350 N m^-1]

Four objects are situated along the y axis as follows: a 2.08kg object is at 2.90 m,a 3.03kg object is at 2.40m,a 2.56 kg object is at the origin,and a 4.05 kg object is at 0.508m.Where is the centre of mass of these objects?

x=

y=

A capillary tube is immersed in water of surface tension 7.2 and the water rises 6.2cm in the capillary tube . what will be the difference in the mercury level if the Same capillary tube is immersed in mercury