1. A jet aircraft with a mass of 4,375 kg has an engine that exerts a force (thrust) equal to 59,600 N.
(a) What is the jet's acceleration? (Give the magnitude.)
(b)What is the jet's speed after it accelerates for 6 s? (Assume it starts from rest.)
(c) How far does the jet travel during the 6 s?
2. A motorcycle and rider have a total mass equal to 365 kg. The rider applies the brakes, causing the motorcycle to accelerate at a rate of
-6 m/s2.
What is the net force on the motorcycle? (Indicate the direction with the sign of your answer.)
3.In an experiment performed in a space station, a force of 77 N causes an object to have an acceleration equal to 3 m/s2. What is the object's mass?
4. On aircraft carriers, catapults are used to accelerate jet aircraft to flight speeds in a short distance. One such catapult takes a 18,100-kg jet from 0 to 68 m/s in 2.8 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?
(d) How large is the force that the catapult must exert on the jet?
5. An airplane is built to withstand a maximum acceleration of 7 g. If its mass is 1,290 kg, what size force would cause this acceleration?
6. 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 84 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.
Weight of person
Net force from part(a)
7. A race car rounds a curve at 57 m/s. The radius of the curve is 439 m, and the car's mass is 605 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?
8. A hang glider and its pilot have a total mass equal to 137 kg. While executing a 360° turn, the glider moves in a circle with a 9 m radius. The glider's speed is 14 m/s. (Assume the glider turns along the horizontal plane.)
(a) What is the net force on the hang glider?
(b) What is the acceleration?
9. As a spacecraft approaches a planet, the rocket engines on it are fired (turned on) to slow it down so it will go into orbit around the planet. The spacecraft's mass is 2,075 kg and the thrust (force) of the rocket engines is 365 N. If its speed must be decreased by 1,184 m/s, how long (in minutes) must the engines be fired? (Ignore the change in the mass as the fuel is burned.)
10. As a baseball is being caught, its speed goes from 32 to 0 m/s in about 0.009 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? (Indicate the direction with the sign of your answer.)
What is the baseball's acceleration in g's? (Indicate the direction with the sign of your answer.)
(b) What is the size of the force acting on it?
11. 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. As the rocket ascends, fuel is burned at a faster rate resulting in a larger acceleration.
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 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.
D. The faster a rocket moves the more acceleration is imparted to it from a given force.
12. We have studied four different laws authored by Sir Isaac Newton. For each of the following, indicate which law is best for the task described.
(a) Calculating the net force on a car as it slows down.
A. the law of universal gravitation
B. Newton's second law
C. Newton's third law
D. Newton's first law
(b) Calculating the force exerted on a satellite by the Earth.
A. Newton's third law
B.Newton's first law
C. the law of universal gravitation
D. Newton's second law
(c) Showing the mathematical relationship between mass and weight.
A. Newton's third law
B. Newton's second law
C. the law of universal gravitation
D. Newton's first law
(d) Explaining the direction that a rubber stopper takes after the string that was keeping it moving in a circle overhead is cut.
a. Newton's third law
b. Newton's second law
c. Newton's first law
d. the law of universal gravitation
(e) Explaining why a gun recoils when it is fired.
a. Newton's third law
b. Newton's first law
c. Newton's second law
d. the law of universal gravitation
(f) Explaining why a wing on an airplane is lifted upward as it moves through the air.
A. Newton's third law
b. Newton's first law
c. Newton's second law
d. the law of universal gravitation
14. What is force?
A. Force is a push or a pull that usually causes distortion and/or acceleration.
B. Force is the ability to do work.
C. Force is the change in velocity with respect to time.
D. Force is the product of mass and velocity.
Identify several of the forces that are acting on or around you. (Select all that apply.)
A. weight (force of gravity) pulling down on everything
B. force of friction holding nails and screws in desks, cabinets, walls, etc.
C. force of friction between you and your seat
D. force of momentum keeping your car moving
E. chemical force in a car battery which allows a car to crank