my model cannot run when i apply a force to the front wheels [closed]

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Hi; I'm a gazebo novice user, i try to run my first example without success. can any body tell me why my car cannot run away when i set a forces to the front wheels please?

herein my model

model.sdf

<?xml version='1.0'?>
      <sdf version='1.4'>
     <model name='car'>
      <static>false</static>
      <link name='chassis'>
          <pose>0 0 0.8 0 0 0</pose>
          <collision name='collision'>
              <geometry>
                  <box>
                      <size>4 2 1</size>
                  </box>
              </geometry>
              <surface>
                  <friction>
                      <ode>
                          <mu>0</mu>
                          <mu2>0</mu2>
                          <fdir1>0 0 0</fdir1>
                          <slip1>0</slip1>
                          <slip2>0</slip2>
                      </ode>
                  </friction>
              </surface>
          </collision>
          <visual name='visual'>
              <geometry>
                  <box>
                      <size>4 2 1</size>
                  </box>
              </geometry>
              <material>
                  <lighting>1</lighting>
                  <script>
                      <uri>file://media/materials/scripts/gazebo.material</uri>
                      <name>Gazebo/Grey</name>
                  </script>
                  <shader type='vertex'>
                      <normal_map>__default__</normal_map>
                  </shader>
                  <ambient>0.3 0.3 0.3 1</ambient>
                  <diffuse>0.7 0.7 0.7 1</diffuse>
                  <specular>0.01 0.01 0.01 1</specular>
                  <emissive>0 255 255 1</emissive>
              </material>
              <transparency>0</transparency>
              <cast_shadows>1</cast_shadows>
          </visual>

          <collision name='collision_top'>
              <pose>0 0 0.8 0 0 0</pose>
              <geometry>
                  <box>
                      <size>1 2 0.6</size>
                  </box>
              </geometry>
              <surface>
                  <friction>
                      <ode>
                          <mu>0</mu>
                          <mu2>0</mu2>
                          <fdir1>0 0 0</fdir1>
                          <slip1>0</slip1>
                          <slip2>0</slip2>
                      </ode>
                  </friction>
              </surface>
          </collision>
          <visual name='visual_top'>
              <pose>0 0 0.8 0 0 0</pose>
              <geometry>
                  <box>
                      <size>1 2 0.6</size>
                  </box>
              </geometry>
              <material>
                  <lighting>1</lighting>
                  <script>
                      <uri>file://media/materials/scripts/gazebo.material</uri>
                      <name>Gazebo/Grey</name>
                  </script>
                  <shader type='vertex'>
                      <normal_map>__default__</normal_map>
                  </shader>
                  <ambient>0.3 0.3 0.3 1</ambient>
                  <diffuse>0.7 0.7 0.7 1</diffuse>
                  <specular>0.01 0.01 0.01 1</specular>
                  <emissive>255 0 255 1</emissive>
              </material>
          </visual>
      </link>

      <link name='wheel_front_left'>
          <pose>1.5 1.3 0.6 0 1.5707 1.5707</pose>
          <collision name='collision'>
              <geometry>
                  <cylinder>
                      <radius>0.6</radius>
                      <length>0.3</length>
                  </cylinder>
              </geometry>
              <surface>
                  <friction>
                      <ode>
                          <mu>0</mu>
                          <mu2>0</mu2>
                          <fdir1>0 0 0</fdir1>
                          <slip1>0</slip1>
                          <slip2>0</slip2>
                      </ode>
                  </friction>
              </surface>
          </collision>
          <visual name='visual'>
              <geometry>
                  <cylinder>
                      <radius>0.6</radius>
                      <length>0.3</length>
                  </cylinder>
              </geometry>
              <material>
                  <lighting>1</lighting>
                  <script>
                      <uri>file://media/materials/scripts/gazebo.material</uri>
                      <name>Gazebo/Grey</name>
                  </script>
                  <shader type='vertex'>
                      <normal_map>__default__</normal_map>
                  </shader>
                  <ambient>0.3 0.3 0.3 1</ambient>
                  <diffuse>0.7 0.7 0.7 1</diffuse>
                  <specular>0.01 0.01 0.01 1</specular>
                  <emissive>0 0 0 1</emissive>
              </material>
          </visual>
      </link>
      <link name='wheel_back_left'>
          <pose frame=''>-1.5 1.3 0.6 0 1.5707 1.5707</pose>
          <collision name='collision'>
              <geometry>
                  <cylinder>
                      <radius>0.6</radius>
                      <length>0.3</length>
                  </cylinder>
              </geometry>
              <surface>
                  <friction>
                      <ode>
                          <mu>0</mu>
                          <mu2>0</mu2>
                          <fdir1>0 0 0</fdir1>
                          <slip1>0</slip1>
                          <slip2>0</slip2>
                      </ode>
                  </friction>
              </surface>
          </collision>
          <visual ...