Python ブロック崩し

ボールがブロックとぶつかると通り抜けました。跳ね返したいですけど、どうすればいいですか？

import
1import pygame
2from pygame.locals import QUIT
3from pygame.locals import Rect
4import math
5pygame.init()
6SURFACE = pygame.display.set_mode((400,300))
7pygame.display.set_caption("Game Window")
8FPSCLOCK = pygame.time.Clock()
9class Block:
10    def __init__(self, color, rect):
11        self.color = color
12        self.rect = rect
13    def draw(self):
14        pygame.draw.rect(SURFACE, self.color, self.rect)
15    def delete(self):
16        blocks.remove(block)
17class Ball:
18    def __init__(self,a,b,c,d):
19        self.color=a
20        self.rect=b
21        self.dir=c
22        self.speed=d
23    def draw(self):
24        pygame.draw.ellipse(SURFACE, ball_color, ball_rect)
25    def move(self):
26        ball_rect.centerx += math.cos(math.radians(self.dir))*self.speed
27        ball_rect.centery -= math.sin(math.radians(self.dir))*self.speed
28        if ball_rect.centerx <=0 or ball_rect.centerx >= 400:
29            self.dir = 180 - self.dir
30        if ball_rect.centery <= 0 or ball_rect.centery >= 300:
31            self.dir = -self.dir
32left=6
33top=30
34width=45
35height=20
36color=(200,50,200)
37blocks = []
38for i in range(4):
39    for j in range(8):
40        rect = Rect(left, top, width, height)
41        blocks.append(Block(color, rect))
42        left += 49
43    left = 6
44    top += 24
45ball_rect = Rect(150,100,10,10)
46ball_color = (255,255,0)
47ball = Ball(ball_color, ball_rect, 60, 5)
48num=0
49while True:
50    SURFACE.fill((0,0,0))
51    for event in pygame.event.get():
52        if event.type == QUIT:
53            pygame.quit()
54            sys.exit()
55    for block in blocks:
56        block.draw()
57    ball.draw()
58    ball.move()
59    for block in blocks:
60        if ball.rect.colliderect(block.rect)==True:
61            Block.delete(blocks)
62            print("{}回目の衝突".format(num))
63            num += 1
64    pygame.display.update()
65    FPSCLOCK.tick(60)
66コード