Answer:
(a) 1.054 m/s²
(b) 1.404 m/s²
Explanation:
0.5·m·g·cos(θ) - μs·m·g·(1 - sin(θ)) - μk·m·g·(1 - sin(θ)) = m·a
Which gives;
0.5·g·cos(θ) - μ·g·(1 - sin(θ) = a
Where:
m = Mass of the of the block
μ = Coefficient of friction
g = Acceleration due to gravity = 9.81 m/s²
a = Acceleration of the block
θ = Angle of elevation of the block = 20°
Therefore;
0.5×9.81·cos(20°) - μs×9.81×(1 - sin(20°) - μk×9.81×(1 - sin(20°) = a
(a) When the static friction μs = 0.610 and the dynamic friction μk = 0.500, we have;
0.5×9.81·cos(20°) - 0.610×9.81×(1 - sin(20°) - 0.500×9.81×(1 - sin(20°) = 1.054 m/s²
(b) When the static friction μs = 0.400 and the dynamic friction μk = 0.300, we have;
0.5×9.81·cos(20°) - 0.400×9.81×(1 - sin(20°) - 0.300×9.81×(1 - sin(20°) = 1.404 m/s².
Answer:
Explanation:
The work done on a particle by external forces is defined as:
According to Newton's second law 
. Thus:
Acceleration is defined as the derivative of the speed with respect to time:
Speed is defined as the derivative of the position with respect to time:
Kinetic energy is defined as 
:
Answer:
Power = Work / Time
P = m g h / t = 80 kg * 9.8 m/s^2 * 15 m / 39 s = 320 N m/ s = 392 J / s
= 392 Watts
Answer:
t=1.87s
b. 9.74
Explanation:
First to find time set an equation for angular velocity:
Now to find the angle:
