英语翻译1 Which is a vector quantity?(1) electric charge(2) elec

英语翻译
1 Which is a vector quantity?
(1) electric charge
(2) electric field strength
(3) electric potential difference
(4) electric resistance
5 A machine launches a tennis ball at an angle of
25° above the horizontal at a speed of 14 meters
per second.The ball returns to level ground.
Which combination of changes must produce an
increase in time of flight of a second launch?
(1) decrease the launch angle and decrease the
ball’s initial speed
(2) decrease the launch angle and increase the
ball’s initial speed
(3) increase the launch angle and decrease the
ball’s initial speed
(4) increase the launch angle and increase the
ball’s initial speed
11 A 0.15-kilogram baseball moving at 20.meters per
second is stopped by a catcher in 0.010 second.
The average force stopping the ball is
(1) 3.0 × 10–2 N (3) 3.0 × 101 N
(2) 3.0 × 100 N (4) 3.0 × 102 N
12 A spring with a spring constant of 80.newtons
per meter is displaced 0.30 meter from its
equilibrium position.The potential energy
stored in the spring is
(1) 3.6 J (3) 12 J
(2) 7.2 J (4) 24 J
16 Which statement best describes a proton that is
being accelerated?
(1) It produces electromagnetic radiation.
(2) The magnitude of its charge increases.
(3) It absorbs a neutron to become an electron.
(4) It is attracted to other protons.
18 If the distance separating an electron and a
proton is halved,the magnitude of the
electrostatic force between these charged
particles will be
(1) unchanged (3) quartered
(2) doubled (4) quadrupled
21,If the amplitude of a wave traveling in a rope is
doubled,the speed of the wave in the rope will
(1) decrease
(2) increase
(3) remain the same
25 As a transverse wave travels through a medium,
the individual particles of the medium move
(1) perpendicular to the direction of wave travel
(2) parallel to the direction of wave travel
(3) in circles
(4) in ellipses