7) A dynamite blast at a quarry launches a chunk of rock straight upward, and 2.

Question

7) A dynamite blast at a quarry launches a chunk of rock straight upward, and 2.3 s later it is rising at a speed of 20 m/s. Assuming air resistance has no effect on the rock, calculate its speed at (a) at launch and (b) 5.5 s after the launch.

8) A woman on a bridge 93.0 m high sees a raft floating at a constant speed on the river below. She drops a stone from rest in an attempt to hit the raft. The stone is released when the raft has 8.90 m more to travel before passing under the bridge. The stone hits the water 5.80 m in front of the raft. Find the speed of the raft.

m/s

9) A snowmobile moves according to the velocity-time graph shown in the drawing. What is the snowmobile's average acceleration during each of the segments A, B, and C? The scale for the time axis is 50 s per increment, and the scale for the velocity axis is 430 m/s per increment.

segment A m/s2
segment B m/s2
segment C m/s2

***(First selection is for negative or positive, middle box is for the value and last selection is for the units h, km/h^2, km, h/km, h/km^2)

at lunch m/s at 5.5 s after launch m/s A dynamite blast at a quarry launches a chunk of rock straight upward, and 2.3 s later it is rising at a speed of 20 m/s. Assuming air resistance has no effect on the rock, calculate its speed at (a) at launch and (b) 5.5 s after the launch. A woman on a bridge 93.0 m high sees a raft floating at a constant speed on the river below. She drops a stone from rest in an attempt to hit the raft. The stone is released when the raft has 8.90 m more to travel before passing under the bridge. The stone hits the water 5.80 m in front of the raft. Find the speed of the raft. A snowmobile moves according to the velocity-time graph shown in the drawing. What is the snowmobile's average acceleration during each of the segments A, B, and C? The scale for the time axis is 50 s per increment, and the scale for the velocity axis is 430 m/s per increment. A bus makes a trip according to the position?time graph shown in the illustration. What is the average acceleration of the bus for the entire 3.5-h period shown in the graph? ***(First selection is for negative or positive, middle box is for the value and last selection is for the units h, km/h^2, km, h/km, h/km^2)

Explanation / Answer

a) v=u+at
20=u+(-9.8)x1.6
u=20+15.68
u=35.68m/s

b)v=u+at
v=35.68+(-9.8)4.7
v=35.68-46.06
v=-10.38m/s
The rock would be falling back at the velocity of 10.38m/s

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