1. An object weighs3000 N. What is the object's mass? _______kg
2. An object weighs 2700 lb. What is the object's weight in N? _______N
3. An object weighs 3500 N. What is the object's weight in lb? _______lb
4. The mass of a certain elephant is 2,667 kg. (a) Find the elephant's weight in newtons. _______N
(b) Find its weight in pounds. _______lb
5. A jet aircraft with a mass of 4,275 kg has an engine that exerts a force (thrust) equal to 59,400 N.
(a) What is the jet's acceleration? (Give the magnitude.) ________
(b)What is the jet's speed after it accelerates for 9 s? (Assume it starts from rest.) ________
(c) How far does the jet travel during the 9 s? ________
6. 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? (Indicate the direction with the sign of your answer.) ________
7. In an experiment performed in a space station, a force of 62 N causes an object to have an acceleration equal to 2 m/s2. What is the object's mass? ________
8. 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? ________
(d) How large is the force that the catapult must exert on the jet? __________
9. An airplane is built to withstand a maximum acceleration of 7g. If its mass is1,210 kg, what size force would cause this acceleration?
_________
10. 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.
Weight of person _________
Net force from
part(a) _________
11.
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? _________
12.
A hang glider and its pilot have a total mass equal to 128 kg. While executing a 360° turn, the glider moves in a circle with a 9 m radius. The glider's speed is 13 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? ____________
13.
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 1,925 kg and the thrust (force) of the rocket engines is 345 N. If its speed must be decreased by 1,134 m/s, how long (in minutes) must the engines be fired? (Ignore the change in the mass as the fuel is burned.) ___________
14.
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? (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?___________
15.
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.)
__The faster a rocket moves the more acceleration is imparted to it from a given force.
__The rocket's mass decreases as its fuel is consumed. The same net force acting on a smaller mass results in a larger acceleration.
__As the rocket ascends, fuel is burned at a faster rate resulting in a larger acceleration.
__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.
16.
A person is riding on a train while watching the display on a GPS unit. The person notices that both the "speed" and the "heading" readings are not changing. What can the person conclude about the net force acting on the train car?
17.
A car starts at positionx = 0, with an initial velocity of 4.7 m/s and an acceleration of 0 m/s2. What is its position when the elapsed time is 6.5 s? (Please be sure to include units in your answer. Express your answer to one decimal point.) ________
18.
A car has an initial position of x = 0 m, an initial velocity of 0 m/s, and a constant acceleration of 2.6 m/s2. What is its position when the time is 4.2 seconds? (Please be sure to include units in your answer. Express your answer to one decimal point.) ________
19.
A car has an initial position ofx = 0 m,an initial velocity of 0 m/s, and a constant acceleration of 4.1 m/s2. What is its velocity when the time is 5.7 seconds? (Please be sure to include units in your answer. Express your answer to one decimal point.)