Chapter 6 Homework
Suppose a ball of putty moving horizontally with 1 kg·m/s of momentum collides with and sticks to an identical ball of putty moving vertically with 1 kg·m/s of momentum. What is the magnitude of their combined momentum?
1.41 kg·m/s
A hungry fish is about to have lunch at the speeds shown. Assume the hungry fish has a mass 5 times that of the small fish. (a) Immediately after lunch, for each case, rank from greatest to least the speed of the formerly hungry fish
Greatest Middle Least v=4m/s v=4m/s v=4m/s V=6m/s V=3m/s V=3/s
How much impulse stops a 42-kg carton sliding at 4.0 m/s when it meets a rough surface?
J = 170 N⋅s 42*4.0= 168 (rounded to 170)
In which is momentum conserved: an elastic collision or an inelastic collision?
Momentum is conserved in elastic and inelastic collisions.
Which exerts the greater impulse on a steel plate- machine gun bullets that bounce from the plate, or the same bullets squashing and sticking to the plate?
The bounce of the plate, as you have a larger impulse and greater momentum change because you are reversing the direction.
In terms of impulse and momentum, why do air bags in cars reduce the chances of injury in accidents?
They are important to have has they cause change in momentum. Air bags increase the time the force is applied and decrease the force, so the result is a lesser force for a longer duration.
An ostrich egg of mass m is tossed at a speed v into a sagging bed sheet and is brought to rest in a time t. (a).An ostrich egg of mass m is tossed at a speed v into a sagging bed sheet and is brought to rest in a time t. (b) If the mass of the egg is 1.4 kg , its initial speed is 2.5 m/s , and the time to stop is 0.20 s, find the average force on the egg.
a. F=MV/T b. F = 18 N
a. Imagine that you replace the block in the video with a happy or sad ball identical to the one used as a pendulum, so that the sad ball strikes a sad ball and the happy ball strikes a happy ball. The target balls are free to move, and all the balls have the same mass. In the collision between the sad balls, how much of the balls' kinetic energy is dissipated? B. Now, consider the collision between two happy balls described in Part A. How much of the balls' kinetic energy is dissipated?
a. Half of it b. None of it
A. Before you click "Play," predict what will happen if the red and green truck with equal mass and equal magnitude of velocity collide. B. Predict what will happen if you reduce the magnitude of the velocity of the green truck to a magnitude smaller than that of the red truck. C. Click "Reset." Now, predict what will happen if you change the velocity of the red truck so that it has a magnitude smaller than that of the green truck but is negative. D. Click "Reset." Now, predict what will happen if you change the velocity of the red truck so that it has a magnitude smaller than that of the green truck but is positive. E. Click "Reset." Now, predict what will happen if you increase the mass of the green truck so that it is greater than the mass of the red truck.
a. The trucks will stick together after the collision and not move. b. The trucks will stick together after the collision and move to the left c. The trucks will stick together after the collision and move to the right. d. The trucks will stick together after the collision and move to the right. e. The trucks will stick together after the collision and move to the right.
a. How is Dr. Hewitt able to break a piece of wood in his demonstration? b. How does Dr. Hewitt break the piece of wood? c. What would Dr. Hewitt need to have done to exert an even greater force than he did in his karate demonstration?
a.He moves his hand very quickly. b.He causes a change in momentum of his hand over a short period of time. c. Increase the change in momentum, and decrease the time duration.
A boxer rides with the punch so as to reduce _______.
force
Cassy can get more force on the bricks she breaks with a blow of her bare hand when _______.
her hand is made to bounce from the bricks.
A slowly moving ship can have a greater momentum than a fast-moving racing car when _______.
its mass times velocity is greater than that of the car.
What is the momentum of an 7.4-kg bowling ball rolling at 2.8 m/s ?
p = 21 kg⋅m/s
What impulse occurs when an average force of 15 N is exerted on a cart for 3.0 s ?
p = 45 kg⋅m/s
The quantity that is called impulse can be measured by the _______.
product of force and time.
When a big fish swims into an oncoming smaller fish and swallows it, the momentum of the two-fish system _______.
remains the same.
A 4.2-kg fish swimming 0.60 m/s swallows an absentminded 1.0-kg fish swimming toward it at a speed that brings both fish to a halt immediately after lunch.
v = 2.5 m/s
When two vehicles collide, momentum is conserved _______.
whether the collision is elastic or inelastic.
