The same 2 kg ball is allowed to roll down two different ramps, one inclined at 15 degrees and the other at 70 degrees. The ball begins at rest at the top of each ramp.

In free body diagrams, draw the force vectors for each ramp and calculate, in newtons: a) the magnitude of the normal force, b) the magnitude of the downward force under the ball due to gravity (I.e., it’s weight) and, c) the magnitude of the net, resultant force accelerating the ball down the ramp.

Respuesta :

a) Normal force in the 1st case: 18.9 N, in the 2nd case: 6.7 N

b) The weight of the two balls is 19.6 N

c) The net force along the ramp is: 5.1 N (1st ball), 18.4 N (2nd ball)

Explanation:

a)

The free-body diagram for the two ramps is shown in attachment. Note that the diagram for the two balls is exactly the same, the only difference is the magnitude of the angle of the ramp, [tex]\theta[/tex] (15 degrees in one case, 70 degrees in the other case).

In order to calculate the magnitude of the normal force (N), we have to study the forces acting in the direction perpendicular to the ramp. We have two forces:

  • The normal force, N, acting upward
  • The component of the weight of the ball perpendicular to the ramp, downward, of magnitude [tex]mgcos \theta[/tex], where m is the mass, g the acceleration of gravity

Since the ball is in equilibrium in this direction, the net force is zero, so the equation of the forces is:

[tex]N-mg cos \theta = 0[/tex]

Where

m = 2 kg

[tex]g=9.8 m/s^2[/tex]

For the first ball, [tex]\theta=15^{\circ}[/tex], so the normal force is

[tex]N_1 = mg cos \theta = (2)(9.8)(cos 15^{\circ})=18.9 N[/tex]

For the second ball, [tex]\theta=70^{\circ}[/tex], so the normal force is

[tex]N_2 = mg cos \theta = (2)(9.8)(cos 70^{\circ})=6.7 N[/tex]

2)

The magnitude of the downward force acting on the ball, which is the force of gravity, is given by

[tex]F=mg[/tex]

where

m is the mass of the ball

g is the acceleration of gravity

We see that its value does not depend on the angle of the ramp, so it is the  same for the two balls. We have:

m = 2 kg

[tex]g=9.8 m/s^2[/tex]

Therefore the weight of the two balls is

[tex]F=(2)(9.8)=19.6 N[/tex]

3)

In this problem, we have to analyze the forces acting in the direction parallel to the ramp.

We have only one force acting in this direction, down along the ramp: the component of the weight parallel to the ramp, which is given by

[tex]F=mg sin \theta[/tex]

m = 2 kg is the mass

[tex]g=9.8 m/s^2[/tex]

For the 1st ball, we have:

[tex]F=(2)(9.8)(sin 15^{\circ})=5.1 N[/tex]

For the 2nd ball, we have

[tex]F=(2)(9.8)(sin 70^{\circ})=18.4 N[/tex]

Learn more about ramps:

brainly.com/question/5884009

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