Answer:
F = 51.3°
Explanation:
The component of weight parallel to the inclined plane must be responsible for the rolling back motion of the car. Hence, the force required to be applied by the child must also be equal to that component of weight:

where,
W = Weight of Wagon = 150 N
θ = Angle of Inclinition = 20°
Therefore,

<u>F = 51.3°</u>
Answer:
A. 4,9 m/s2
B. 2,0 m/s2
C. 120 N
Explanation:
In the image, 1 is going to represent the monkey and 2 is going to be the package. Let a_mín be the minimum acceleration that the monkey should have in the upward direction, so the package is barely lifted. Apply Newton’s second law of motion:

If the package is barely lifted, that means that T=m_2*g; then:

Solving the equation for a_mín, we have:

Once the monkey stops its climb and holds onto the rope, we set the equation of Newton’s second law as it follows:
For the monkey: 
For the package: 
The acceleration a is the same for both monkey and package, but have opposite directions, this means that when the monkey accelerates upwards, the package does it downwards and vice versa. Therefore, the acceleration a on the equation for the package is negative; however, if we invert the signs on the sum of forces, it has the same effect. To be clearer:
For the package: 
We have two unknowns and two equations, so we can proceed. We can match both tensions and have:

Solving a, we have

We can then replace this value of a in one for the sums of force and find the tension T:

Answer:x=23.4 cm
Explanation:
Given
mass of block 
inclination 
coefficient of static friction 
coefficient of kinetic friction 
distance traveled 
spring constant 
work done by gravity+work done by friction=Energy stored in Spring






Answer:
Primero, definimos el desplazamiento como la distancia entre la posición final y la posición inicial.
Así, si comenzamos abajo, luego subimos la escalera, y luego bajamos, la posición final y la posición inicial serán la misma
por lo que el desplazamiento es igual a cero.
La medida recorrida es el espacio total recorrido.
Es decir, si entre el principio y el final de la escalera hay una distancia D.
La persona que sube y baja, recorre esta distancia dos veces.
Entonces cuando una persona sube y baja la escalera, la medida de su trayectoria será 2*D.
Earth's gravity pulls air as close to the surface as possible. As altitude increases, the amount of gas molecules in the air decreases—the air becomes less dense than air nearer to sea level.