Moments after making the dreaded decision to jump out the door of the airplane, Darin's 75.5-kg body experiences +128 N of air resistance upward. Determine Darin's acceleration (in m/s?) at this instant in time. Hint: Your answer will be negative since he is falling (i.e., his acceleration is still in the down direction).

A cart is given an initial velocity of 13.5 m/s and experiences a constant acceleration of 2.5 m/s2. What is the magnitude of the cart's displacement during the first 11 s of its motion?

An object moving with uniform acceleration has a velocity of 11.0 cm/s in the positive x-direction when its x-coordinate is 3.06 cm. If its x-coordinate 2.15 s later is −5.00 cm, what is its acceleration? _____cm/s2   A ball is thrown directly downward with an initial speed of 7.45 m/s, from a height of 30.3 m. After what time interval does it strike the ground? _______s A small mailbag is released from a helicopter that is descending steadily at 2.78 m/s. (a) After 3.00 s, what is the speed of the mailbag? v = ______m/s (b) How far is it below the helicopter? d = ______m (c) What are your answers to parts (a) and (b) if the helicopter is rising steadily at 2.78 m/s? v=______m/s d=______m   A model rocket is launched straight upward with an initial speed of 44.0 m/s. It accelerates with a constant upward acceleration of 1.00 m/s2 until its engines stop at an altitude of 200 m. (a) What can you say about the motion of the rocket after its engines stop? (b) What is the maximum height…

Rocket-powered sleds are been used to test the responses of humans to acceleration. Starting from rest, one sled can reach a speed of 510 m/s in 2.37 s and can be brought to a stop again in 3.15 s. Find the acceleration of the sled while accelerating. Answer in units of m/s2. Find the acceleration of the sled when braking. Answer in units of m/s2.

A boxer's fist and glove have a mass of m = 1.04 kg. The boxer's fist can obtain a speed of v = 9.25 m/s in a time of t = 0.21 s. Write a symbolic expression for the magnitude of the average acceleration, aave, of the boxer's fist, in terms of the variables provided.  Find the magnitude of the average acceleration, aave, in meters per square second. Write an expression for the magnitude of the average net force, Fb, that the boxer must apply to his fist to achieve the given velocity. (Write the expression in terms of m, v and t.) What is the numerical value of Fb, in newtons?

A rocket is initially at rest on the ground. It is launched straight up. As long as the rocket has fuel, it accelerates upwards at a constant rate a. After a time t₁, the rocket uses up its fuel and its engine abruptly stops. Find the maximum height reached by the rocket.

An object moves in the x-y plane with a constant acceleration of 2i +3j meters per second squared. The object starts at the origin with some initial velocity. After four seconds (4 seconds) the velocity of the object is 2i + 8j meters per second. Determine the object’s initial velocity. Leave answer in i-j notation. Determine the position of the object at time, t = 4 seconds. Leave answer in i-j notation.   Thank you for your help.

1. Assume that air resistance is proportional to speed. A parachutist falls from rest. If he did not open his parachute, he would reach a terminal velocity of 90 m/s. With an open parachute, he reaches a terminal velocity of 10 m/s. He opens his parachute 20 s after he started falling. Calculate (a) The distance already fallen at the moment when he opens his parachute; (b) The total distance fallen 40 s after he started falling.