下面关于力学现象的解释中,正确的是( )
A:大力士不能凭空把自己举起来,说明力是使物体运动的原因
B:汽车上坡,没有向上的推力或拉力,车会向下运动,说明车此时没有惯性
C:物体在空中自由下落,速度越来越快,说明力是改变物体运动状态的原因
D:球在草地上越滚越慢,说明力的作用效果只能改变物体运动速度的大小
(2015.福建莆田)
Enjoy Harvesting
Want to relax yourself?
Want to experience country life?
Come and pick litchi!
Free for a taste.
Price:¥20 per kilo Dates: July 20th-July 28th
Add: Changlin village Tel:277-8688
Fitness Band on sale
Smartwatches without the watch
Monitor speed, time, distance, caloties burned, etc.
Long battery(电池)life (5 days)
¥800 (20% off for students)
Tel:289-6799
Visit Sam Mall for more information.
Ice and Snow Festival
Charming Ice Carving
Amazing World of Ice and Snow
Welcome to Fenghuang Park!
Dates: July 1st -July 25th
¥20 for each adult (half for each student)
Tel:288-6299
Super Pillow(枕头)Fight Party
Pillow Fight, a popular activity among young foreigners, has now come to Putian. It's a creative way to release(释放) pressure and stress.
Place:Putian Stadium
Time:2:30-5:00pm, June 28th
Fee:¥50 (pillow included)
Tel:275-6588
如图所示是一辆质量为1.2t的小汽车,以72km/h速度在一段平直公路匀速行驶了1h,油耗为6kg,它所受的阻力是车重的0.1倍(假设汽油完全燃烧,热值q=4.6×107J/kg).
—______.