Assignment:
1. A motorcycle and rider have a total mass equal to 335 kg. The rider applies the brakes, causing the motorcycle to accelerate at a rate of -4 m/s2. What is the net force on the motorcycle?
2. On aircraft carriers, catapults are used to accelerate jet aircraft to flight speeds in a short distance. One such catapult takes a 17,800-kg jet from 0 to 67 m/s in 2.7 s. (Assume the catapult acts in the positive horizontal direction. Indicate the direction with the sign of your answer where appropriate.)
(a) What is the acceleration of the jet in m/s2?
(b) What is the acceleration of the jet in g's?
(c) How far does the jet travel while it is accelerating?
3. An airplane is built to withstand a maximum acceleration of 7g. If its mass is1,210 kg, what size force would cause this acceleration?
4. Under certain conditions, the human body can safely withstand an acceleration of 10 g.
(a) What net force would have to act on someone with mass of 75 kg to cause this acceleration?
(b) First, find the weight of such a person in pounds. Second convert the answer obtained in part (a) into pounds.
5. A race car rounds a curve at 55 m/s. The radius of the curve is 434 m, and the car's mass is 685 kg. (Assume the car's speed remains constant. Take the radially inward direction to be positive. Indicate the direction with the sign of your answer.)
(a) What is the car's (centripetal) acceleration?
(b) What is it in g's?
(c) What is the centripetal force acting on the car?
6. As a baseball is being caught, its speed goes from 27 to 0 m/s in about 0.008 s. Its mass is 0.145 kg. (Take the direction the baseball is thrown to be positive.)
(a) What is the baseball's acceleration in m/s2?
What is the baseball's acceleration in g's?
(b) What is the size of the force acting on it?
7. As a rocket ascends, its acceleration increases even though the net force on it stays constant. Why? (Assume a traveling distance small enough that the thrust, acceleration due to gravity and atmosphere do not change.)
a. The faster a rocket moves the more acceleration is imparted to it from a given force.
b. The rocket's mass decreases as its fuel is consumed. The same net force acting on a smaller mass results in a larger acceleration.
c. As the rocket ascends, fuel is burned at a faster rate resulting in a larger acceleration.
d. As a rocket ascends it's momentum increases with it's speed. The greater the momentum of the rocket, the greater the acceleration imparted to it from a given force.