Dùng một bếp điện để đun nóng một nổi đụng 2kg nước đá ở nhiệt độ t_{1} = - 20 ^ 0 * C thì nước đã bắt đầu nóng chảy. (Cho nhiệt dung riêng của nước da c 1 =2100 J/kg. K . Sau 2,1 phút , của nước C_{2} = 4200J/kg. K, nhiệt nóng chảy của nước đá lambda nd =3,4.10^ 5 J/kg Coi việc cung cấp nhiệt diễn ra một cách đều đặn và bỏ qua mọi hao phí nhiệt ra môi trường xung quanh, nhiệt cung cấp cho nổi.) Sau bao lâu kể từ khi bắt đầu đun thì nước đá nóng chảy hoàn toàn? A. B. Đến khi nước đá nóng chảy hoàn toàn, người ta đổ thêm vào nồi 0, 5 kg nước ở 30 ^ 0 * C . Tính tổng nhiệt lượng bếp đã cung cấp để / lượng nước trong nồi hóa hơi hoàn toàn?(nhiệt hóa hơi của nước L=2,3.10^ 6 J/kg)

Which are examples of projectile motion? choose all that apply a. a soccer ball rolling across the ground in the northeast direction b. a car turning a corner, so it is heading south c. a javelin flying through the air d. a tennis ball lobbed over the net

Ablock of mass 1.5 kg slides down an inclined plane that has an angle of 15. if the inclined plane has no friction and the block starts at a height of 3 m, how much kinetic energy does the block have when it reaches the bottom? acceleration due to gravity is g = 9.8 m/s2. a. 6.8 j b. 50.9 j c. 0 j d. 44.1 j

Aplane flies a distance d from west to east at a constant speed vp , with respect to the air in a time twe . on the return trip, the plane flies a distance d from east to west at a constant speed vp , with respect to the air in a time tew . on both trips the wind blows from west to east at a constant speed va , with respect to the ground 1) what is tew in terms of vp, va, and d, as needed? tew=dvp tew=dvp+va tew=dva tew=dvpâ’va tew=12dvp tew=12dvp+va tew=12dvpâ’va your submissions: b submitted: saturday, january 26 at 6: 49 pm feedback: feedback will be given once all questions have been attempted and the grade cluster button has been pressed. 2) what is twe in terms of vp, va, and d, as needed? twe=dvp twe=dvp+va twe=dva twe=dvpâ’va twe=12dvp twe=12dvp+va twe=12dvpâ’va your submissions: d submitted: saturday, january 26 at 6: 49 pm feedback: feedback will be given once all questions have been attempted and the grade cluster button has been pressed. 3) assuming d = 2300 miles, vp = 400 miles/hr, and twe = 4 hours, what is va, the speed of the wind with respect to the ground? va = 100 miles/hr va = 575 miles/hr va = 200 miles/hr va = 175 miles/hr va = 975 miles/hr 4) once again, assuming d = 2300 miles, vp = 400 miles/hr, and twe = 4 hours, what is tew, the time it takes the plane to fly a distance d miles from east to west? tew = 5.75 hours tew = 11.5 hours tew = 7.67 hours tew = 8 hours tew = 10.2 hours