Answer:
6.58m
Explanation:
The kinetic energy = Workdone on the roller
Workdone = Force * distance
Given
KE = Workdone = 362J
Force = 55N
Required
Distance
Substitute into the formula;
Workdone = Force * distance
362 = 55d
d = 362/55
d = 6.58m
Hence the student must push at a distance of 6.58m
Answer:
71 rpm
Explanation:
Given that:
Angular momentum (L) = 0.26
Diameter = 25cm = 0.25 cm
Radius, r = (d/2) = 0.125m
Mass = 5.6 kg
Moment of inertia (I) = 2mr² / 5
I = (2 * 5.6 * 0.125^2) / 5
= 0.175
= 0.175 / 5
= 0.035 kgm²
Angular speed (w) ;
w = L / I
w = 0.26 / 0.035
= 7.4285714
= 7.429 rad/s
w = (7.429 * 60/2π)
w = 445.74 / 2π rpm
w = 70.941724
Angular speed = 70.94 rpm
= 71 rpm
Answer:
a)
Y0 = 0 m
Vy0 = 15 m/s
ay = -9.81 m/s^2
b) 7.71 m
c) 3.06 s
Explanation:
The knowns are that the initial vertical speed (at t = 0 s) is 15 m/s upwards. Also at that time the dolphin is coming out of the water, so its initial position is 0 m. And since we can safely assume this happens in Earth, the acceleration is the acceleration of gravity, which is 9.81 m/s^2 pointing downwards
Y(0) = 0 m
Vy(0) = 15 m/s
ay = -9.81 m/s^2 (negative because it points down)
Since acceleration is constant we can use the equation for uniformly accelerated movement:
Y(t) = Y0 + Vy0 * t + 1/2 * a * t^2
To find the highest point we do the first time derivative (this is the speed:
V(t) = Vy0 + a * t
We equate this to zero
0 = Vy0 + a * t
0 = 15 - 9.81 * t
15 = 9.81 * t
t = 0.654 s
At this time it will have a height of:
Y(0.654) = 0 + 15 * 0.654 - 1/2 * 9.81 * 0.654^2 = 7.71 m
The doplhin jumps and falls back into the water, when it falls again it position will be 0 again. So we can equate the position to zero to find how long it was in the air knowing that it started the jump at t = 0s.
0 = Y0 + Vy0 * t + 1/2 * a * t^2
0 = 0 + 15 * t - 1/2 * 9.81 t^2
0 = 15 * t - 4.9 * t^2
0 = t * (15 - 4.9 * t)
t1 = 0 This is the moment it jumped into the air
0 = 15 - 4.9 * t2
15 = 4.9 * t2
t2 = 3.06 s This is the moment when it falls again.
3.06 - 0 = 3.06 s
Answer:
36.87 km/h
Explanation:
Convert all the units in SI system
1 mile = 1609.34 m
d1 = 6 mi = 9656.04 m
t1 = 15 min = 15 x 60 = 900 s
d2 = 3 mi = 4828.02 m
t2 = 10 min = 10 x 60 = 600 s
d3 = 1 mi = 1609.34 m
t3 = 2 min = 2 x 60 = 120 s
d4 = 0.5 mi = 804.67 m
t4 = 0.5 min = 0.5 x 60 = 30 s
Total distance, d = d1 + d2 + d3 + d4
d = 9656.04 + 4828.02 + 1609.34 + 804.67 = 16898.07 m = 16.898 km
total time, t = t1 + t2 + t3 + t4
t = 900 + 600 + 120 + 30 = 1650 s = 0.4583 h
The ratio of the total distance covered to the total time taken is called average speed.
Average speed = 16.898 / 0.4583 = 36.87 km/h
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