Ball Animation in Landscape mode for iPhone

Question

I'm animating a ball on the screen in portrait mode using UIAccelerometer.

It's working fine, now I want the same to work in landscape mode. When I tried to use the same part of code (for portrait) in the landscape mode it gives me a weird result, seems to be completely wrong.

My code below is for portrait view.

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {   
    // apply acceleration to velocity

    NSTimeInterval elapsedTime = acceleration.timestamp - lastAccelTimestamp;     
    ballVelocityX = ballVelocityX + (acceleration.x * MAX_ACCEL_PER_SEC * elapsedTime);    
    ballVelocityY = ballVelocityY - (acceleration.y * MAX_ACCEL_PER_SEC * elapsedTime);

    if (lastAccelTimestamp > 0) {    
        // recalc ball position  
        ballX += (ballVelocityX * elapsedTime); // ballX is CGFloat   
        ballY += (ballVelocityY * elapsedTime); // ballY is CGFloat    
        // update view    
        [ballView setCenter:CGPointMake(ballX, ballY)];   
    }
    lastAccelTimestamp = acceleration.timestamp;
}