Answer:
v = 11 m/s is her final speed
Explanation:
work done by gravity = m g Δh = 40×9.8×10 = 3920 Joules
Work done by friction = - force×distance = - 20×100 = - 2000 Joules
[minus sign because friction force is opposite to the direction of motion]
Initial K.E. = (1/2) m u^2 = (1/2) × 40 × 5^2 = 500 Joules
Now, by work energy theorem
Work done = change in kinetic energy.
Final K.E. = initial K.E. + total work = 500 + 3920 - 2000 = 2420 Joules
Now, Final K.E. = (1/2) m v^2 [final speed being v= speed at the bottom]
⇒ 2420 = (1/2)×40×v^2
⇒ 121 = v^ 2
v = 11 m/s is her final speed
22. a - (vf^2 - vi^2)/(2d)
a = (0 - 23^2)/(170)
a = -3.1 m/s^2
23. Find the time (t) to reach 33 m/s at 3 m/s^2
33-0/t = 3
33 = 3t
t = 11 sec to reach 33 m/s^2
Find the av velocuty: 33+0/2 = 16.5 m/s
Dist = 16.5 * 11 = 181.5 meters to each 33m/s speed. Runway has to be at least this long.
24. The sprinter starts from rest. The average acceleration is found from:
(Vf)^2 = (Vi)^2 = 2as ---> a = (Vf)^2 - (Vi)^2/2s = (11.5m/s)^2-0/2(15.0m) = 4.408m/s^2 estimated: 4.41m/s^2
The elapsed time is found by solving
Vf = Vi + at ----> t = vf-vi/a = 11.5m/s-0/4.408m/s^2 = 2.61s
25. Acceleration of car = v-u/t = 0ms^-1-21.0ms^-1/6.00s = -3.50ms^-2
S = v^2 - u^2/2a = (0ms^-1)^2-(21.0ms^-1)^2/2*-3.50ms^-2 = 63.0m
26. Assuming a constant deceleration of 7.00 m/s^2
final velocity, v = 0m/s
acceleration, a = -7.00m/s^2
displacement, s - 92m
Using v^2 = u^2 - 2as
0^2 - u^2 + 2 (-7.00) (92)
initial velocity, u = sqrt (1288) = 35.9 m/s
This is the speed pf the car just bore braking.
I hope this helps!!
Answer:
that there would be more clouds.
Explanation:
one of the cycles is precipitation. without water there would be no rain and clouds are what causes the rain to come down
Since the direction of the needle depends on the proximity of the magnet thus this test alone is insufficient to determine the stronger magnet.
<h3>What is a magnetic field?</h3>
A magnetic field refers to the region where the effect of a magnet is felt. The magnetic field can be observed by the use of a compass.
Now, we know that the closer the magnet is to the compass, the greater the deflection hence this test alone is insufficient to determine the stronger magnet.
Learn more about magnetic field:brainly.com/question/14848188
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Answer:
<em> -11,813.87N </em>
Explanation:
According to coulombs law, the Force between the two charges is expressed as;
F = kq1q2/d²
k is the coulombs constant = 9*10⁹kg⋅m³⋅s⁻²⋅C⁻².
q1 = -0.00067 C
q2 = 0.00096 C
d = 0.7m
Substitute into the formula:
F = 9*10^9 * -0.00067 * 0.00096/0.7²
F = 9*10⁹*-6.7*10⁻⁴*9.6*10⁻⁴/0.49
F = -578.88*10⁹⁻⁸/0.49
F = -578.88*10/0.49
F = -5788.8/0.49
F = -11,813.87N
<em>Hence the force between the two charges is -11,813.87N </em>
