Answer:
p = mv
Explanation:
The momentum of an object is given by the equation:
where
m is the mass of the object
v is the velocity
Since velocity is a vector, it follows that momentum is a vector as well, therefore it has a magnitude and a direction (the same as the velocity).
The SI unit of the momentum is 
An important law related to the momentum is the law of conservation of momentum, which states that for an isolated system (= zero net external force on it), the total momentum of the system is conserved.
Answer:
Explanation:
When the rock is immersed in unknown liquid the forces that act on it are shown as under
1) Tension T by the string
2) Weight W of the rock
3) Force of buoyancy due to displaced liquid B
For equilibrium we have 
=
When the rock is suspended in air for equilibrium we have
When the rock is suspended in water for equilibrium we have
+ 
=
Using the given values of tension and solving α,β,γ simultaneously for 
we get
Solving for density of liquid we get
Answer:
392 N
Explanation:
Draw a free body diagram of the rod. There are four forces acting on the rod:
At the wall, you have horizontal and vertical reaction forces, Rx and Ry.
At the other end of the rod (point X), you have the weight of the sign pointing down, mg.
Also at point X, you have the tension in the wire, T, pulling at an angle θ from the -x axis.
Sum of the moments at the wall:
∑τ = Iα
(T sin θ) L − (mg) L = 0
T sin θ − mg = 0
T = mg / sin θ
Given m = 20 kg and θ = 30.0°:
T = (20 kg) (9.8 m/s²) / (sin 30.0°)
T = 392 N
