HELP ME I’M DESPERATE PHYSICS EASY 40 POINTSS 1.A car moving with a speed of 108 km/h is brought to rest in a distance of 60 m. How m

Question

HELP ME I’M DESPERATE PHYSICS EASY 40 POINTSS
1.A car moving with a speed of 108 km/h is brought to rest in a distance of 60 m. How much time did the car take to stop?
2 seconds
4 seconds
6 seconds
8 seconds

2.A student standing on the ground next to a tall building throws a ball straight up with a speed of 39.2 m/s. If it takes the ball 4 seconds to reach the same height as the top of the building, how tall is the building?
a.44.1 m
b.78.4 m
c.161.7 m
d.235.2 m
3.A boy throws a ball with an initial velocity of 19.6 m/s and it returns to his hands in 4 seconds. What maximum height does the ball reach?
4.9 m
9.8 m
19.6 m
39.4 m

in progress 0
Thu Cúc 3 years 2021-09-04T01:10:46+00:00 1 Answers 10 views 0

Answers ( )

  1. Thunguyet
    0
    2021-09-04T01:11:58+00:00
    Reply

    Answer:

    see below

    Explanation:

    1. 108km/hr

    = 108/3.6

    = 30m/s

    30m/s = 0 m/s average speed

    = 30/2

    = 15m/s

    t = 60 minutes/15(meters/second)

    = 4 seconds (the second option)

    2.  Height of building = (v^2 – u^2)/2g

    = (0 – (39.2 * 39.2) / (2 * ( – 9.8))

    = 78.4 m (option B)

    3.Use vf^2 = vi^2 + 2as

    0 = 384.16 – 19.6s

    19.6s = 384.16

    s  = 19.6 m (option C)

    4.

    Time taken to walk first 1 Km= 1/5 hr

    Time taken to walk second 1 Km = 1/7 hr

    Speed = Distance travelled/time

    Speed =2/ (1/5 + 1/7)

    = 2/(12/35)

    = 2 x 35/12

    = 35/6

    = 5.8 Km/hr (the first option)

    Hope this helps, and please mark me brainliest if it does!

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )