In large mine openings, How air velocities are common because of the large open-space volume
In large mine openings, How air velocities are common because of the large open-space volume
In large mine openings, low air velocities ( ) are common because of the large open-space volume
In large mine openings, low air velocities ( ) are common because of the large open-space volume
In large mine openings, How air velocities are common because of the large open-space volume A: 正确 B: 错误
In large mine openings, How air velocities are common because of the large open-space volume A: 正确 B: 错误
At a instant, the magnitudes of velocities of points [img=14x19]1803a110c41a5ac.png[/img] and [img=14x19]1803a110ccca93a.png[/img] in a plane figure are [img=19x17]1803a110d54e8f5.png[/img] and [img=19x17]1803a110de4a0df.png[/img] , respectively, and [img=61x17]1803a110e6ea33c.png[/img]. Which drawings are impossible for the velocity directions? A: [img=208x229]1803a110f15ab6d.png[/img] B: [img=210x229]1803a110fbaf808.png[/img] C: [img=215x229]1803a11105c64ec.png[/img] D: [img=208x250]1803a11111be725.png[/img]
At a instant, the magnitudes of velocities of points [img=14x19]1803a110c41a5ac.png[/img] and [img=14x19]1803a110ccca93a.png[/img] in a plane figure are [img=19x17]1803a110d54e8f5.png[/img] and [img=19x17]1803a110de4a0df.png[/img] , respectively, and [img=61x17]1803a110e6ea33c.png[/img]. Which drawings are impossible for the velocity directions? A: [img=208x229]1803a110f15ab6d.png[/img] B: [img=210x229]1803a110fbaf808.png[/img] C: [img=215x229]1803a11105c64ec.png[/img] D: [img=208x250]1803a11111be725.png[/img]
A small sphere [img=14x19]1803277aebb0146.png[/img] with mass m moves from the same height to the ground along three different paths. It is assumed that the initial velocity is zero and all frictions can be neglected. If the velocities of the sphere when it reaches the ground are [img=16x17]1803277af50bf6c.png[/img], [img=15x17]1803277afd4c34c.png[/img] and [img=15x17]1803277b05a80ad.png[/img]，respectively, then[img=613x182]1803277b133657e.png[/img] A: [img=92x23]1803277b1bc7064.png[/img] B: [img=92x23]1803277b24d87f0.png[/img] C: [img=92x17]1803277b2d043c5.png[/img] D: [img=92x23]1803277b35385b3.png[/img]
A small sphere [img=14x19]1803277aebb0146.png[/img] with mass m moves from the same height to the ground along three different paths. It is assumed that the initial velocity is zero and all frictions can be neglected. If the velocities of the sphere when it reaches the ground are [img=16x17]1803277af50bf6c.png[/img], [img=15x17]1803277afd4c34c.png[/img] and [img=15x17]1803277b05a80ad.png[/img]，respectively, then[img=613x182]1803277b133657e.png[/img] A: [img=92x23]1803277b1bc7064.png[/img] B: [img=92x23]1803277b24d87f0.png[/img] C: [img=92x17]1803277b2d043c5.png[/img] D: [img=92x23]1803277b35385b3.png[/img]