test Physic
A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in
.5 s
It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?
10 N
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about
10 m/s
A ball on the end of a string is whirled with constant speed in a counterclockwise horizontal circle as shown in the figure. At point A, the string breaks. Which of the curves shows the path of the ball after the string breaks?
2
A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. The average braking force is
2000 N
A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set?
40 J
One half second after starting from rest, a freely falling object will have a speed of about
5 m/s
A car initially travels west with a kinetic energy of 10 J. Then it travels east at three times its original speed. What is its kinetic energy when it is traveling east?
90 J
True or False: A car moves with constant speed of 100 km/hr. It's acceleration must be zero.
F
True or False: Impulse and momentum are the same thing.
F
True or False: Suppose that the speed of a ball moving in a horizontal circle is increasing at a steady rate. This increase in speed is a result of the centripetal acceleration.
False
True of False: An object moving in a circle with constant speed is accelerating.
T
True or False: A car traveling around a curve with constant speed is accelerating.
True
Disregarding air resistance, objects fall with constant
acceleration
For an object moving in a circle with constant speed, there is
centripetal acceleration
True or False: A tennis ball following a parabolic trajectory without air resistance has two forces acting on it; gravity downward and a force keeping it moving forward.
false
In each second of a fall, the distance a freely falling object will fall is
increasing
Twelve seconds after starting from rest, an object falling freely will have a speed of
more than 100 m/s
An astronaut, floating alone in outer space, throws a baseball. If the ball floats away at a speed of 20 meters per second, the astronaut will
move in the opposite direction , but a t a lower speed
A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?
the dropped one
A 1000-kg car and a 2000-kg car are hoisted the same distance. Raising the more massive car requires
twice as much work
