Studied by 1 personA car travels around a flat (nonbanked) curve with constant speed, turning leftwards. In which direction is the net force on the car?
leftwards
Two cars travel around the same curve, a red one at twice the speed of a blue car. After traveling the same distance, which car, if either, has experienced a larger change in velocity?
the red car
Two masses are separated by a distance r. If the distance is doubled how does the force between them change, if at all?
it is reduced by a factor of 4.
A car travels the same distance at the same constant speed around two curves, one with twice the radius of curvature of the other. In which, if either, of these curves, does the car have the largest change in velocity?
the curve with the smaller curvature
Suppose that the speed of a ball moving in a horizontal circle is increasing at a steady rate. Is this increase in speed produced by the centripetal acceleration?
no
A car travels around a curve with a constant speed. What, if anything, happens to the velocity of the car in this process?
its direction changes
A car travels around a curve with a constant speed. Is the car accelerating?
yes
If a ball is whirled in a vertical circle with constant speed, at what point in the circle, if any, is the tension in the string greatest?
the bottom of the cirrcle
How does an increased length of time that a force acts on an object affect the strength of the impulse produced?
increases
If you were standing on a cart that was at rest and free to roll (ignore friction) and someone threw a 10 kg ball at you, you would
roll backward faster if the ball bounced off of you elastically.
Two ice skaters, initially at rest push off one another. What sign is the total momentum of the system after they push off?
zero
The momentum of a truck is increased by a factor of 2; its weight does not change. Thus,
its speed doubled
Is it possible for a system to have energy if nothing is moving in the system?
yes
Moving at a constant speed, an elevator lifts a 1000 N package 10 meters in 3 seconds. During this time, the impulse delivered to the package by the elevator floor is
3,000 Ns up
A bowling ball, moving to the east at a speed of 1.4 m/s, collides head-on with a stationary beach ball of the same diameter but less than one twentieth the mass. After the collision, the beach ball moves with a speed of 1.6 m/s. Which of the following is then true?
The bowling ball has a velocity of slightly under 1.4 m/s, to the east.
Although Newton's second law, F = ma, is valid for collisions, it is difficult to use it generally in this form for collisions because
the force F is not constant and the acceleration occurs during a time interval too short to measure easily.
Suppose you are out on a frozen lake, where there is no friction. Which of the following would start you moving towards the shore?
removing a shoe and throwing it away from the shore
Is there an advantage to following through when hitting a baseball with a bat, thereby maintaining a longer contact between the bat and the ball?
\n Yes, this increases the change in momentum of the baseball.
Which has the greater kinetic energy—a 1-ton car moving at 30 m/s or a half-ton car moving at 60 m/s?
the half-ton car
A rocket obeys the principles of recoil. However, it is much more difficult to apply Newton's second law to a rocket because
as the rocket motor fires the total mass of the rocket changes.
Which of the following mathematical expressions should be used to calculate the momentum of an auto?
mass x velocity
Initially, a blue automobile has twice the kinetic energy that a red automobile has. Both are braked to a stop; both have the same amount of braking force. The red auto will stop in ____________________ as the blue auto.
1/2 the distance
The purpose of an air bag in an auto is to
decrease the force applied to you during a collision.
A railroad car collides and couples with a second railroad car that is standing still. If the external forces acting on the two cars are negligible, how will the velocity of the first car change after the collision?
The velocity of the first car will decrease.
One form of the proper metric unit for momentum is
N*sec
A 30-kg child runs at 3.0 m/s and jumps onto a shopping cart and holds on for dear life. The cart has a mass of 20 kg. Assuming the child rides on the cart after the collision, the speed of the child and shopping cart just after the child jumps on is
1.8 m/s
During a collision, which of these is an indication that the total kinetic energy has changed?
heat is generated
deformation occurs
sound is produced
A pendulum is pulled back from its equilibrium (center) position and then released. What form of energy is added to the system prior to its release?
GPE
A pendulum is pulled back from its equilibrium (center) position and then released. At what points in the motion of the pendulum after release is its kinetic energy greatest?
center point
A pendulum is pulled back from its equilibrium (center) position and then released. At what is the potential energy the greatest?
highest point in the swing
A tennis ball bounces off a brick wall. Which of the following is true?
The total momentum of the ball, wall, and Earth is conserved in this process
If you catch a baseball or softball with your bare hand, how, if at all, will the force exerted on the ball change if you lower your hand in the direction of the movement of the ball as you are catching the ball?
it decreases the force
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