Answer: D
Explanation: read the answers above and compare to your test
Answer:
a)P= -4800 i
b)F= 0
Explanation:
Given that
r = (4570-160 t) i + 2930 j + 130 k
We know that velocity is rate of change of the space vector.
V= dr/dt
r = (4570-160 t) i + 2930 j + 130 k
dr/dt= -160 i + 0 + 0
dr/dt= -160 i
V= -160 i
It means that velocity is in only x-direction
We also know that acceleration is the rate of change of velocity .
a= dV/dt
V= -160 i
dV/dt=0
So we can say that acceleration is zero.
a= 0
From Second law of Newton'
Force = Mass x acceleration
F= 300 x 0
F= 0
We know that linear momentum P
P = m V
Given that m= 300 kg
P = 300 x (-160 i)
P= -4800 i
The answer is a B Light wave can travel in a vacuum and travel at a contest speed even if the light source is moving
Answer:
The friction force and the x component for the weight should be the reaction forces that are opposite and equal to the action force, which causes the locomotive to move up the hill if the velocity of the locomotive remains constant.
Explanation:
<u>When the locomotive starts to pull the train up, appears two reaction forces opposed to the action force in the direction of the move. </u>
The first one is due to the friction between the wheels and the ground, it will be the friction force (Fr):
Fr = μ*Pₓ =μmg*sin(φ)
<em>where μ: friction dynamic coefficient, Pₓ: is the weight component in the x-axis, m: total mass = train's mass + locomotive's mass, g: gravity, and sin(φ): is the angle respect to the x-axis.</em>
And the second one is the x component for the weight (Wₓ):
Wₓ = mg*cos(φ)
<em>where cos(φ): is the angle respect to the y-axis. </em>
<em> </em>
These two forces should be the same as the action force, which causes the locomotive to move up the hill if the velocity of the locomotive remains constant.
