A physical change can be distinguished from a chemical change because during a physical change- A. the properties of the substance may change, but no new substances are produced B. the properties of the substance change for only a short time but will return to their original state. C. an entirely new substance with new properties forms as a result of the change D. a new substance is produced, but the new substance has properties identical to the original substance.

hi,

what occurs during a solar eclipse?

there are small tides across earth.

the moon is between earth and the sun.

p.s. im not sure if the first answer is correct because during a solar ecliphse there are spring tides and i dont know if they are the same.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.