can you help me answer this?

Question

Sprinting near the end of a race, a runner with a mass of 65 kg accelerates from a speed of 6 m/s to a speed of 7 m/s in 2 s.

(a) What is the runner's average acceleration during this time?
m/s2

(b) To gain speed the runner produces a backward force on the ground, so that the ground pushes the runner forward providing the force necessary for acceleration. Calculate this average force.
N

The air exerts a forward force of 10 N on the propeller of a 0.40 kg model airplane. If the plane accelerates forward at 4.0 m/s2, what is the magnitude of the resistive force exerted by the air on the airplane?
N


A boat moves through the water with two forces acting on it. One is a 1500 N forward push by the motor, and the other is an 1100 N resistive force due to the water.

(a) What is the acceleration of the 900 kg boat?
m/s 2

(b) If it starts from rest, how far will it move in 6.0 s?
m

(c) What will its velocity be at the end of this time?
m/s

Answer 1

1. delta V / delta t or change in velocity divided by change in time. 1meter per second divided by 2 seconds = .5m/seconds squared
2) F=ma or Force (in newtons) = mass (in kg) times the acceleration (im m/s2) or .5*65 pr 32.5N
3 force 1 +force 2 or 10N + .4*4.0 or 11.6 N
4A) 1500N-1100N = 400N forward F=ma or in this case a=m/F or 900kg/400N = 2.25 meters per second squared.
B)a=V/t and V=S/t therefore a=s/t2 therefore S=at2 or 2.25*36 or 81 meters
c)2.25*6 or 13.5m/s

Answer 2

i hav no idea