Answer:
-20.0 m/s and 30.0 m/s
Explanation:
Momentum is conserved:
m (30.0) + m (-20.0) = m v₁ + m v₂
30.0 − 20.0 = v₁ + v₂
10.0 = v₁ + v₂
Since the collision is perfectly elastic, energy is also conserved. Since there's no rotational energy or work done by friction, the initial kinetic energy equals the final kinetic energy.
½ m (30.0)² + ½ m (-20.0)² = ½ mv₁² + ½ mv₂²
(30.0)² + (-20.0)² = v₁² + v₂²
1300 = v₁² + v₂²
We now have two equations and two variables. Solve the system of equations using substitution:
1300 = v₁² + (10 − v₁)²
1300 = v₁² + 100 − 20v₁ + v₁²
0 = 2v₁² − 20v₁ − 1200
0 = v₁² − 10v₁ − 600
0 = (v₁ + 20) (v₁ − 30)
v₁ = -20, 30
If v₁ = -20, v₂ = 30.
If v₁ = 30, v₂ = -20.
So either way, the final velocities are -20.0 m/s and 30.0 m/s.
Answer:
The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object. The frictional force from a fluid is called a drag force.
Explanation:
Answer:
most probably 5120J. or 32000x0.8= 25600J
Explanation:
the 1st machine has 20% efficiency. if we supply 32000 joules to the 1st machine then the work output is 32000x0.2 = 6400 J.
if this output from the 1st machine with an output of 6400J is passed through the second machine with an efficiency of 80% then we get 6400x.80 = 5120J.
