change url by fuction in PyQt5 Webview

Question

from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import *
from PyQt5.QtCore import *
from time import sleep

class MainWindow(QMainWindow):
def __init__(self):
    QMainWindow.__init__(self)
    self.ui = Ui_MainWindow()
    self.ui.setupUi(self)

    self.ui.start_btn.clicked.connect(self.startbtn)
    self.ui.set_btn.clicked.connect(self.setbtn)
    self.ui.quit_btn.clicked.connect(self.quitbtn)
    self.ui.btn_close.clicked.connect(QCoreApplication.instance().quit)
    self.ui.btn_maximize.clicked.connect(lambda: self.showMinimized())
    self.show()

def show_web(self, url):
    self.ui.webvideo.setUrl(QUrl(url))

def startbtn(self):
    # self.ui.stacked.setCurrentWidget(self.ui.page_video)
    self.show_web('https://www.youtube.com')
    sleep(1)
    self.show_web('https://www.google.com')

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    app.exec_()

I try to change PyQt5 webview url by show_web() but it only show last url(https://www.google.com) I want to see (https://www.google.com) for a second