Answer:
Friction opposes motion.
Explanation:
If there is relative motion, the frictional force is the kinetic force of friction.
Answer:
the number of additional car lengths approximately it takes the sleepy driver to stop compared to the alert driver is 15
Explanation:
Given that;
speed of car V = 120 km/h = 33.3333 m/s
Reaction time of an alert driver = 0.8 sec
Reaction time of an alert driver = 3 sec
extra time taken by sleepy driver over an alert driver = 3 - 0.8 = 2.2 sec
now, extra distance that car will travel in case of sleepy driver will be'
S_d = V × 2.2 sec
S_d = 33.3333 m/s × 2.2 sec
S_d = 73.3333 m
hence, number of car of additional car length n will be;
n = S_n / car length
n = 73.3333 m / 5m
n = 14.666 ≈ 15
Therefore, the number of additional car lengths approximately it takes the sleepy driver to stop compared to the alert driver is 15
-- If it's all happening horizontally, then gravity is not involved.
Only the spring is.
-- If there's no friction, then total energy is conserved.
-- If you put 190J of energy into the spring by moving the mass,
and there's only 55J of potential energy in the spring now, then
the other 135J of energy is in the kinetic energy of the mass and
the moving parts of the spring.
Answer:
h ’= 12,768 cm
Explanation:
For this exercise let's use the constructor equation
1 / f = 1 / p + 1 / q
where f is the focal length, p the distance to the object and q the distance to the image
the magnification equation is
m = h '/ h = -q / p
let's find the distance to the object
1 / p = 1 / f- 1 / q
1 / p = 1/20 - 1 / (- 37.5)
1 / p = 0.076666
p = 13.04 cm
now let's use the magnification equation
h ’= - q / p h
let's calculate
h ’= - (-37.5) / 13.04 4.44
h ’= 12,768 cm
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