Playing with LÖVE's physics engine for the first time

I thought I'd make sure today that Lua Carousel correctly handles LÖVE's physics libraries. No issues! And then my son suggested I could turn the example in the LÖVE tutorial into a very simple game. Not for a touchscreen, unfortunately. Here's the code:

ph = love.physics
ph.setMeter(64)
world = ph.newWorld(0, 9.81*64, true)
objects = {}
objects.ground = {}
objects.ground.body = ph.newBody(world, Safe_width/2, Safe_height/2)
objects.ground.shape = ph.newRectangleShape(Safe_width-200, 50)
objects.ground.fixture = ph.newFixture(objects.ground.body, objects.ground.shape)
objects.ball = {}
objects.ball.body = ph.newBody(world, Safe_width/2,0, "dynamic")
objects.ball.shape = ph.newCircleShape(20)
objects.ball.fixture = ph.newFixture(objects.ball.body, objects.ball.shape, --[[density]] 1)
  objects.ball.fixture:setRestitution(0.9) -- bounce
objects.block1 = {}
objects.block1.body = ph.newBody(world, Safe_width*3/4, Safe_height/2-100, 'dynamic')
objects.block1.shape = love.physics.newRectangleShape(0, 0, 50, 100)
objects.block1.fixture = love.physics.newFixture(objects.block1.body, objects.block1.shape, 1)
objects.block2 = {}
objects.block2.body = ph.newBody(world, Safe_width*3/4, Safe_height/2-200, 'dynamic')
objects.block2.shape = ph.newRectangleShape(0, 0, 100, 50)
objects.block2.fixture = ph.newFixture(objects.block2.body, objects.block2.shape, 1)
function car.update(dt)
  world:update(dt)
  if objects.block1.body:getY() > Safe_height/2 and objects.block2.body:getY() > Safe_height/2 then
    Result = 'You win!'
  elseif objects.ball.body:getY() > Safe_height/2 then
    Result = 'You lost!'
  end
end
Result = ''
function car.draw()
  if Result == '' then
    color(0.4, 0.4, 0.4)
    g.print('a: push left', 50,30)
    g.print('l: push right', 50,60)
    g.print('u: try again', 50,90)
  elseif Result:find('lost') then
    color(1,0,0)
    g.print(Result, 50,50)
  elseif Result:find('win') then
    color(0,0,1)
    g.print(Result, 50,50)
  end
  color(0.28, 0.63, 0.05)
  poly('fill', objects.ground.body:getWorldPoints(objects.ground.shape:getPoints()))
  color(0.76, 0.18, 0.05)
  circle('fill', objects.ball.body:getX(), objects.ball.body:getY(), objects.ball.shape:getRadius())
  color(0.20, 0.20, 0.20)
  poly('fill', objects.block1.body:getWorldPoints(objects.block1.shape:getPoints()))
  poly('fill', objects.block2.body:getWorldPoints(objects.block2.shape:getPoints()))
end
function car.keypressed(key)
  if key == 'l' then
    objects.ball.body:applyForce(400, 0)
  elseif key == 'a' then
    objects.ball.body:applyForce(-400, 0)
  elseif key == 'u' then
    objects.ball.body:setPosition(Safe_width/2, 0)
    objects.ball.body:setLinearVelocity(0, 0)
    Result = ''
  end
end

As before, you'll need to either run the abbreviations screen in the examples or paste in these up top:

g = love.graphics
circle, poly = g.circle, g.polygon
color = g.setColor