牛頓運動定律

A trolley of mass $1$ kg placed on a smooth horizontal table is connected by two light strings to blocks $A$ and $B$ of masses $0.75$ kg and $0.25$ kg respectively, as shown in the figure. $X$ and $Y$ are frictionless pulleys. When the system is released, what will be its acceleration ?

Five blocks of equal mass $A$, $B$, $C$, $D$ and $E$ are connected by four identical strings $S_1$, $S_2$, $S_3$ and $S_4$ as shown in the figure above. They are made to slide on a smooth horizontal surface by a steadily increasing force $F$ applied to block $A$. Which of the strings is most likely to break first ?

Two blocks $A$ and $B$ of masses $m_1$ and $m_2$ are connected by a light spring on a horizontal frictionless table. The spring is stretched by moving the blocks apart. What is the ratio of the acceleration of $A$ to that of $B$ at the moment when they are released ?

An object is resting on a rough plane inclined at an angle $\theta$ to the horizontal. As $\theta$ gradually increases, the frictional force acting on the object before sliding occurs is directly proportional to

A horizontal force $F$ is applied to a block of mass $M$ on a rough horizontal surface. The acceleration of the block is $a$. If the force is changed to $2F$ and the frictional force remains unchanged, then the acceleration of the block will be

In the figure, $X$ and $Y$ are blocks of mass $1$ kg and $2$ kg respectively. $S$ is a spring balance of negligible mass and $P$ is a smooth pulley fixed at the top of two smooth inclined planes. What is the reading of $S$ when $X$ is held stationary by an external force ?

A spring balance suspended from the ceiling of a lift registers the weight of a $20$ kg body as $150$ N. The lift is probably