اسئلة فى الفيزياء الحديثة

[فيزيائية نان]

بسم الله الرحمن الرحيم
السلام عليكم ورحمة الله وبركاته
كيف حالكم يافيزيائيين إن شاء الله دائما بخير ؟
انا عندي اسئلة في مادة "الفيزياء الحديثة" عن النسبية
مافهمتها ولا عرفت كيف احلها !!!!
الله يخليكم ساعدوني لاني مررررررره محتاجتها بأسرع وقت
وأملي بعد الله فيكم كبيييير

والاسئلة هي :

1-If the speed of light were smaller than it is, would relativistic phenomena be more or less conspicuous than they are now ? Why ?0


2-An athlete learned enough physics to know that if he measures from the earth a time interval on a moving spacecraft , what he finds will be greater than what somebody on the spacecraft would measure . He therefore proposes to set a world record for the 100 m dash by having his time taken by an observer on a moving spacecraft . Is this a good idea ?0


3-Two observers, A on earth and B in a spacecraft whose speed is 2*10^8 m/s , both set their watches to the same time when the shop is abreast of the earth
A- How much time must elapse by A’s reckoning before yhe watches differ by 1 s?0
B- To A, B’s watch seems to run slow. To B, does A’s watch seem to run fast, run slow, or keep the same time as his own watch ?0


4- How fast must a spacecraft travel relative to the earth for each day on the spacecraft to correspond to 2 days on the earth ?0