The magnitude of the acceleration of the car is ten times greater than the magnitude of the acceleration of the truck.
A truck rear-ends a car that is initially stationary. The truck weighs ten times more than the car. Which statement is true about the collision?
The glass that falls onto the carpet takes a longer time to stop.
A glass that falls onto a carpeted floor has less chance of breaking than a glass that falls (from the same height) onto a wooden floor. Why?
moves to the left with a speed of 6 m/s
A stationary 100-kg person is initially holding a 50-kg ball while standing on a skateboard. The person throws the ball to the right, and the ball moves (with respect to the ground) with a speed of 12 m/s. The person on the skateboard ____________.
The momenta of the two carts are equal.
Consider two carts, initially at rest. Cart 1 is twice as massive as cart 2. If you push on cart 1 for 3 seconds and then push on cart 2 with the same force for 3 seconds, how do the final momenta of the two carts compare? (Ignore the effect of friction.)
moving to the left with a speed of 8 m/s
A 200-lb person pushes on the back of a 100-lb person. Both people are on skateboards and are initially stationary. After the push, the 200-lb person is moving to the right with a speed of 4 m/s. The 100-lb person is ________.
20 m/s
A car is driving down the highway with an initial speed of 30 m/s. It slams into the back of an identical car (same mass), which was initially going only 10 m/s (in the same direction as the faster car). If the collision is perfectly inelastic, the final speed of the two cars is ________.
its mass times velocity is greater than that of the car.
A slowly moving ship can have a greater momentum than a fast-moving racing car when _______.
The moving skateboard.
Which has a greater momentum: a heavy truck at rest or a moving skateboard?
product of force and time.
The quantity that is called impulse can be measured by the _______.
Impulse is force times a time interval.
Distinguish between force and impulse.
increasing the force or increasing the time interval.
An impulse can be increased by
F=ma=mΔv/Δt, so Ft=Δ(mv)
How is the impulse -momentum relationship related to Newton’s second law?
equal and opposite to the momentum of the fired cannonball.
When a cannonball is fired from a cannon, the momentum of the recoiling cannon is momentarily _______.
transfers its momentum to the 8 ball.
When a cue ball strikes an 8 ball head-on in a game of pool, the cue ball _______.
whether the collision is elastic or inelastic.
When two vehicles collide, momentum is conserved _______.
remains the same.
When a big fish swims into an oncoming smaller fish and swallows it, the momentum of the two-fish system _______.
Yes, always.
Is it correct to say that, if no net impulse is exerted on a system, then no change in the momentum of the system will occur?
vectorally add up to equal the initial momentum of the firecracker
When a falling firecracker explodes, the momenta of its pieces _______.
Momentum is conserved in elastic and inelastic collisions.
In which is momentum conserved: an elastic collision or an inelastic collision?
The speed of car B is equal to the initial speed of A.
Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of car B compare with the initial speed of car A?
Their speed is half the initial speed of car A.
If the equally massive cars of the preceding question stick together after colliding inelastically, how does their speed after the collision compare with the initial speed of car A?
either of these depending on speed
Which has the greater momentum when moving?
a pickup truck speeding along a highway
Which of the following has the largest momentum relative to Earth’s surface?
twice.
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
momentum.
A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater
3 m/s.
The speed of a 4-kg ball with a momentum of 12 kg m/s is
16 kg.
The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is
acceleration.
If several balls are thrown straight up with different initial speeds, the quantity that will have the same value along their paths is their
3,000 kg m/s.
A motorcycle of mass 100 kilograms slowly rolls off the edge of a cliff and falls for three seconds before reaching the bottom of a gully. Its momentum upon hitting the ground is
a corresponding change in momentum.
It is correct to say that impulse is equal to
lengthened time of contact.
Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter
stopping time is longer on the carpet.
Compared with falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the
about 1/10 as great.
When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is
longer time.
If you can’t avoid being hit by a fast-moving object, you’ll suffer a smaller contact force if you can extend that force over a
greater with the brick wall.
Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is
both the same
Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is
cannon has much more mass than the cannonball.
A cannon recoils while firing a cannonball. The speed of the cannon’s recoil is relatively small because the
the target would be safer than the shooter.
A tiny gun made of a strong but very light material fires a bullet more massive than the gun itself. For such a weapon
greater.
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared with the force that stops the car, the force needed to stop the truck is
2000 N.
The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is
a decreasing acceleration.
an increasing speed.
an impulse.
all of the above
an increasing speed.
an impulse.
all of the above
As Bronco Brown steps off a hovering high-flying helicopter and falls through the air, he experiences
decreased.
When bullets are fired from an airplane in the forward direction, the momentum of the airplane is
decreases.
When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard
friction between his feet and the board.
Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard. The reason he doesn’t slip off the skateboard is due to
both the same
You’re driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact
move in the opposite direction at a lower speed.
An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will
zero
Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
decreases.
An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car’s speed
1 kg m/s.
A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of
1 m/s.
A 2-kg rifle that is suspended by strings fires a 0.01-kg bullet at 200 m/s. The recoil velocity of the rifle is about
2/3 m/s
A 5000-kg freight car moving at 2 m/s collides with a 10,000-kg freight car at rest. They couple upon collision and move away at
6 m/s
A 5000-kg freight car collides with a 10,000-kg freight car at rest. They couple upon collision and move at 2 m/s. What was the initial speed of the 5000-kg car?
none of the above
A sandbag motionless in outer space is hit by a three-times-as massive sandbag moving at 12 m/s. They stick together and move at a speed of
all the same
A red car has a head-on collision with an approaching blue car with the same magnitude of momentum. A green car driving with the same momentum as the other cars collides with an enormously massive wall. Which of the three cars will experience the greatest impulse?
at 45 degrees to the direction of either car before collision.
Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The combined wreck moves in a direction
in the vertical direction equals the momentum of the firecracker before bursting.
in the horizontal direction cancels to zero.
both of these
in the horizontal direction cancels to zero.
both of these
When a vertically falling firecracker bursts, the vector sum of momentum fragments
continue along the path as if the explosion didn’t occur.
A cannonball following a parabolic path explodes into fragments. The momentum of the fragments
27 N⋅s
What is the magnitude of the impulse on an 9.0-kg ball rolling at 3.0 m/s when it bumps into a pillow and stops?
