+ 9. What force (in units of Newtons) is needed to give a 3.5 m/s" acceleration to a 1200 kg car?
1 answer:
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Answer:
W = 0
Explanation:
When an electron moves perpendicular to a uniform B-field. If the field is in a vacuum, the magnetic field B is the dominant factor determining the motion. Since the magnetic force F is perpendicular to the direction of travel, an electron follows a curved path in a magnetic field. The electron continues to follow this curved path until it forms a complete circle. Another way to look at this is that the magnetic force F is always perpendicular to velocity v, so that it does no work on the charged particle. The particle’s kinetic energy and speed thus remain constant. The direction of motion is affected but not the speed.
W = F*d*Cos ∅ = F*d*Cos 90° = 0 where d is the displacement.
The pic shown can help to understand the explanation.
Answer:
w = 0.943 rad / s
Explanation:
For this problem we can use the law of conservation of angular momentum
Starting point. With the mouse in the center
L₀ = I w₀
Where The moment of inertia (I) of a rod that rotates at one end is
I = 1/3 M L²
Final point. When the mouse is at the end of the rod
= I w + m L² w
As the system is formed by the rod and the mouse, the forces during the movement are internal, therefore the angular momentum is conserved
L₀ = L_{f}
I w₀ = (I + m L²) w
w = I / I + m L²) w₀
We substitute the moment of inertia
w = 1/3 M L² / (1/3 M + m) L² w₀
w = 1 / 3M / (M / 3 + m) w₀
We substitute the values
w = 1/3 / (1/3 + 0.02) w₀
w = 0.943 w₀
To finish the calculation the initial angular velocity value is needed, if we assume that this value is w₀ = 1 rad / s
w = 0.943 rad / s