1.a) resultant of all the weights acting on the car by the Earth
resultant of the normal and the fricitonal forces.
b) Zx = 11600 N,Zy = 11772 N Z = 16.5 kN
Angle = 45.4
2. Use work done = force x distance moved where force = mg if the mass move at constant speed. Hence work done is change in PE = mgh
ii) AT larger distances away from the Earth mgh can be used provided the g is the value at that location and the distance moved is kept small.
b) The total heat = mL + mc@ = 774 J WHERE @ = 68 deg. and L is latent heat of evaporation.
c) The work done against atm is large as the intermolecular distances is larger from gas to liq . as compared to solid to liq.
3. Do not omit free body diagram. R+mg=mv2/r
where R=0 , v = sq root of rg
vmin = 13.3 ms-1 and entry speed = 29.8 ms-1 and R-mg = mv2/r where R = mg +mv2/r
= 14.8kN.
Take note that the final ke +mgh + Wfriciton= initial KE
b) The magnitude of force at the bottom is greater than the weight as the resultant force is towards the centre.
4. when the freq is below the threshold freq, no photoelectrons are emitted no matter how high the intensity.
Reason : Photon energy is insufficent to overcome work function and hence no emission .Increasing the intensity only increases the number of photons per sec but the photon energy remains the same. hence particulate nature of light.
The uncertainty in time is longer and hence the uncertainty in E is decreased. Hence the energy level is defined.
e) At higher energy the barrier width shorter hence transmission coefficient greater giving shorter average waiting time before tunnelling therefore shorter half-life
5. As temp increases the number charge carrier increases in SC and hence better conductivity. The resistance wire has free electrons whose path are obstructed by lattice vibration and hence greater resistivity.
b) The energy band gap is small and hence electron overcome band gap easily and moved across to Conduction band. The hole left behind at the valence band and electron in conduction band contribute to conduction of charges.
c) The electron diffuse across to the p region creating immobile ions and free of mobile charge carrier.
d) forward biased circuit diagram
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