A. the bullet is propelled by gunpowder gas.
B. the bullet is subjected to inertia.
C. bullets have inertia
D. the inertia of the bullet is greater than the resistance it receives.
Where do people who jump up vertically fall in a train car that travels at a constant speed on a straight track?
A: The person who jumped up still fell back to his original place.
Put a glass of water on the horizontal table on the train. If the water surface changes suddenly, the possible change of the train motion state is [B D].
A. the train suddenly started to the right.
B.the train suddenly started to the left.
C. The train runs to the right at a constant speed and suddenly accelerates to the right.
D. The train runs to the right at a constant speed and suddenly decelerates to the right.
1. All objects have inertia, and the correct one in the following description is ().
A. the inertia of a moving object is greater than that of a stationary object.
The faster an object moves, the greater its inertia.
C. the greater the force on an object, the greater its inertia.
The greater the mass, the greater the inertia.
2. The airplane model that pops up with a rubber band keeps moving forward because ().
A. the aircraft is affected by inertia
B. the rubber band makes the plane elastic.
C. the plane has inertia
D. the inertia of the aircraft is greater than the resistance it receives.
3. A hydrogen balloon hangs a heavy object and rises vertically at a uniform speed of1m/s. In the process of rising, the rope hanging the object suddenly breaks, so after the rope breaks, the object ().
A. it drops immediately, and the speed is increasing.
B. Fall at a constant speed immediately
C due to inertia, the object rises at a constant speed of1m/s.
D. First rise for a certain distance and then fall, and the speed will be faster and faster when falling.
1D 2C 3D