物理牛顿定律英文版.ppt

1. Who was the scientist who gave us the Laws of Motion? Answer: Sir Isaac Newton  2. How many Laws of Motion are there? Answer: three  3. What is another name for the first law of motion? Answer: Law of Inertia  4. Which law explains why we need to wear seat belts? Answer: First Law of Motion One day ,Stephen Su was driving a motorcycle on the street. Meanwhile, David was driving a trunk at a fast speed. Stephen Su did not stop in time as soon as the traffic light turned red. David could not control the van and collided with Stephen. The remaining question is ,even though Stephen slammed on the brake, the accident happened anyway. What caused this tragedy?? According to Newtons first law, an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Newton’s first law of motion牛顿第一定律: Every body continues in its state of uniform motion or rest unless acted up on by an external force Application of the Newton’s first law Safety belts Any passengers in the car will also be decelerated to rest if they are strapped to the car by seat belts. Being strapped tightly to the car, the passengers share the same state of motion as the car. As the car accelerates, the passengers accelerate with it; as the car decelerates, the passengers decelerate with it; and as the car maintains a constant speed, the passengers maintain a constant speed as well. A disk and a hoop of the same mass M and radius R roll without slipping across a horizontal floor. Both the disk and the hoop are moving with velocity v when the floor starts to slope upward. Which statement is correct? ( ) (a)???The disc makes it to a greater height than the hoop. (b)???The hoop makes it to a greater height than the disk.(c)???Both the disk and the hoop make it to the same height. A disk and a hoop of the same mass M and radius R roll without slipping across a horizontal floor. Both the disk and the hoop are moving with velocity