Answer: V = 15 m/s
Explanation:
As stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. The observed frequency the car will be experiencing will be addition of the two frequency. That is,
F = 2.1 × 10^10 + 1030 = 2.100000103×10^10Hz
Using doppler effect formula
F = C/ ( C - V) × f
Where
F = observed frequency
f = source frequency
C = speed of light = 3×10^8
V = speed of the car
Substitute all the parameters into the formula
2.100000103×10^10 = 3×10^8/(3×10^8 -V) × 2.1×10^10
2.100000103×10^10/2.1×10^10 = 3×108/(3×10^8 - V)
1.000000049 = 3×10^8/(3×10^8 - V)
Cross multiply
300000014.7 - 1.000000049V = 3×10^8
Collect the like terms
1.000000049V = 14.71429
Make V the subject of formula
V = 14.71429/1.000000049
V = 14.7 m/s
The speed of the car is 15 m/s approximately
Answer:
16.2 days
Explanation:
Find the number of halflives:
1/2 * 1/2 = 1/4 so <u>two</u> halflives have passed
2 * 8.1 days = 16.2 days
Thermal expansion<span> is the tendency of matter to change in shape, area, and volume in response to a change in temperature, through </span>heat<span> transfer. Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, the kinetic energy of its molecules increases.so this can result in.......heat</span>
Gravitational Potential Energy, GPE = mgh
Where m is your mass in kg, g is acceleration due to gravity = 9.8 m/s², and h is the height in m.
The only value that be controlled here is the height h. The mass is constant, and acceleration due to gravity at that place is constant.
But h can be varied.
Hence to increase the gravitational potential energy between yourself and Earth is to increase the height h.
This can be done by climbing up a table, or climbing up a building through the stairs, or by using a lift.
Answer:
The power dissipated is reduced by a factor of 2
Explanation:
The power dissipated by a resistor is given by:
where
I is the current
R is the resistance
by using Ohm's law, 
, we can rewrite the previous equation in terms of the voltage applied across the resistor (V):
In this problem, the resistance of the element is doubled, while the voltage is kept constant. So we have 
while V remains the same; substituting into the formula, we have:
so, the power dissipated is reduced by a factor 2.
