Answer:
Part a)
![a = 2.4 m/s^2](https://img.qammunity.org/2020/formulas/physics/high-school/v2ya9ci5f02vt8jzk0wan3xailrkbpbdtc.png)
Part b)
![F = 120 N](https://img.qammunity.org/2020/formulas/physics/high-school/6cfx52xaipi2xgveuqxufv9vfy25xaqbnh.png)
Step-by-step explanation:
Two sleds are connected by a rope
mass of each sled is given as
![m = 100 kg](https://img.qammunity.org/2020/formulas/physics/high-school/b2hpc6u9f9df5n0lnzk2avw7zp07dar9px.png)
now we know that dog exert pulling force on the rope connected to first sled
![F = 240 N](https://img.qammunity.org/2020/formulas/physics/high-school/900es1qextgz6u2nmtgdc1eomow9phs6s8.png)
Part a)
By newton's first law we know that
![F = (m + m)a](https://img.qammunity.org/2020/formulas/physics/high-school/6jfiavrcovfwocfhj8d7b3hz5qkoyo27n7.png)
![240 = (100 + 100)a](https://img.qammunity.org/2020/formulas/physics/high-school/c8ss4dyexmbwjkcaweiph59wdpvqky04eh.png)
![a = (240)/(100)](https://img.qammunity.org/2020/formulas/physics/high-school/m9gx50ae2h3qolb0ladq1eztivmnkzvr2z.png)
![a = 2.4 m/s^2](https://img.qammunity.org/2020/formulas/physics/high-school/v2ya9ci5f02vt8jzk0wan3xailrkbpbdtc.png)
Part b)
As we know that force between two ropes will pull the sled behind
so we will have
![F = ma](https://img.qammunity.org/2020/formulas/physics/high-school/6dslirwz7efajuroewtnbxamr1m7rpia2b.png)
![F = 100(1.20)](https://img.qammunity.org/2020/formulas/physics/high-school/z16topf56k3u4xsuzswhvftvuaz6j3ecna.png)
![F = 120 N](https://img.qammunity.org/2020/formulas/physics/high-school/6cfx52xaipi2xgveuqxufv9vfy25xaqbnh.png)