Answer:
D
Explanation:
Because kinetic energy do have more than potential energy: kinetic energy is when a object is moving. Potential energy is when something is at rest and has no movement what so ever
The force of friction is zero.
Using F = m a = the force needed is 6 N which means no friction can be acting.
Answer:
Explanation:
As per Doppler's effect we know that the frequency of the sound that is observed by the detector is the reflected sound
This reflected sound is given as
so we know that the beat frequency is
so we will have
so we have
Answer:
U= 1.9*10^-7
Explanation:
given:
<em>L=8 cm</em>
<em>d_1=d_2=2.05_10^-3</em>
<em>K_py=4.3</em>
<em>K_po=3</em>
<em>V_ab=86 V</em>
required
U=??
solution:
the energy stored in the capacitor
U=1/2C_t*V^2_ab (1)
voltage is known but capacitance is not
we can consider the two plates of polystyrene and pyrex glass as a two separate capacitors connected on series so the total capacitance of series capacitor is given by:
1/C_t= 1/C_py+1/C_po (2)
the capacitance of polystyrene
C_po=K_po*A/d
=8.9*10^-11
= 89 pF
the capacitance of pyrex
C_py=K_py*A/d
=128 pF
substitution in 2 yields
1/C_t= 1/128+1/89
C_t= 52.6 pF
substitution in 1 yields
U=1/2C_t*V^2_ab
= 1.9*10^-7
