Physics help please??// Thanks for the help?

Question

Could someone help me with these problems, because I have a test coming up and these are the suggested problems. Thank you

1) An airplane lands and starts down the runway at a southwest velocity of 45 m/s. What constant acceleration allows it to come to a stop in 1.4 km

2) Two blocks are connected by a lightweight, flexible cord that passes over a frictionless pulley. If m1 is 3.4 kg and m2 is 9.1 kg, and block 2 is initially at rest 140 cm above the floor, how long does it take block 2 to reach the floor?

Answer 1

1) The speed of the plane is 45 m/s second when it lands, and 0 when it stops. The average speed of the plane is 22.5 m/s. Since it takes 1400m to stop, then it stops in 62.22 seconds. So 45 m/s divided by 62.22 seconds is 0.723214 m/s². Note that the plane is decelereating, so the acceleration is negative, -0.723214 m/s²

2) I am rusty on this one. M2 weighs 9.1 kg, but the cable from M1 pulls up on it with a force of 3.4 kg. The effective force on M2 is then 5.7 kg, but but the combined mass of the system is 12.5 kg. Acceleration = Force/Mass
You have to make the units work out right. Acceleration is in m/s² I forget the formula for distance covered under constant acceleration, you should look it up if you don't know it.