12–139. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, d
etermine the minimum acceleration experienced by the passengers.
(60)2
y
2
0)2 = 1
*12–140. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, determine the maximum acceleration experienced by the passengers.
12–142. The race car has an initial speed vA = 15 m> s at
a. If it increases its speed along the circular track at the rate at = (0.4s) m> s2, where s is in meters, determine the time needed for the car to travel 20 m. Take r = 150 m.
x
Probs. 12–139/140
(60)2
y
2
0)2 = 1
*12–140. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, determine the maximum acceleration experienced by the passengers.
12–142. The race car has an initial speed vA = 15 m> s at
a. If it increases its speed along the circular track at the rate at = (0.4s) m> s2, where s is in meters, determine the time needed for the car to travel 20 m. Take r = 150 m.
x
Probs. 12–139/140
1 answer:
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<h3>1)</h3>
No,kinetic energy cannot be negative since its given by KE=mv²,mass cannot be negative and the square of speed cannot b negative.
<h3>2)</h3>Yes,any force opposing motion or displacement does negative work. They are often referred to as resistive forces (friction,air resistance,drag...)
<h3>3)</h3>Nope it does not, it just forces the object to move in a circular path known as a centripetal force. It can accelerate an object by changing it's direction but not it's speed.
<h3>4)</h3>No it cannot,If an object is sliding on the table (assuming it is not an incline), then most probably that normal force cancels out the weights effect or assuming there is an incline, it cancels the weight's y component.
<h3>5)</h3>The work done is zero
<h3>6)</h3>The work is just the product of the magnitude of the force exerted and the displacement of the object.
<h3>7)</h3>Answer:
k_max = 31.82 w/mk
k_min = 17.70 w/mk
Explanation:
a) the maximum thermal conductivity is given as
where k_m is thermal conductvitiy of metal
k_p is thermal conductvitiy of carbide
v_m = proportion of metal in the cement = 0.17
v_p = proportion of carbide in the cement = 0.83
= 66*0.17 + 28*0.83
k_max = 31.82 w/mk
b) the minimum thermal conductivity is given as
= \frac{28+66}{28*0.17 +66*0.83}
k_min = 17.70 w/mk
Answer:
The frequency of this photon is
(D) is correct option.
Explanation:
Given that,
Excited states,
We need to calculate the wavelength
Using formula for energy
We need to calculate the frequency
Using formula of frequency
Where, E =energy
Hence, The frequency of this photon is