Before you even look at the questions, look over the graph, so you know what kind of information is there.
The x-axis is "time". OK. You know that as the graph moves from left to right, it shows what's happening as time goes on.
The y-axis is "speed" of something. OK. When the graph is high, the thing is moving fast. When the graph is low, the thing is moving slow. When the graph slopes up, the thing is gaining speed. When the graph slopes down, the thing is slowing down. When the graph is flat, the speed isn't changing, so the thing is moving at a constant speed.
NOW you can look at the questions.
OMG ! It's only ONE question: What's happening from 'c' to 'd' ? Well I don't know. Perhaps we can figure it out if we LOOK AT THE GRAPH !
-- Between c and d, the graph is flat. The speed is not changing. It's the same speed at d as it was back at c .
What speed is it ?
-- Look back at the y-axis. The speed at the height of c and d is 'zero' .
-- The 2nd and 4th choices are both correct. From c to d, <em>the speed is constant</em>. The constant speed is zero. <em>The car is not moving</em>.
Answer:
28.7%
Explanation:
efficiency = work output /work input × 100
La magnitud es de 9.8 m/s² ... la aceleración de la gravedad en o cerca de la superficie de la Tierra.
La dirección es hacia el centro de la Tierra. (Llamamos a esa dirección "abajo").
Answer:
Explanation:
Let the vertical height by which it descends be h . Let it acquire velocity of v .
1/2 mv² = mgh
v² = 2gh
As it leaves the surface of sphere , reaction force of surface R = 0 , so
centripetal force = mg cosθ where θ is the angular displacement from the vertex .
mv² / r = mg cosθ
(m/r )x 2gh = mg cosθ
2h / r = cosθ
cosθ = (r-h) / r
2h / r = r-h / r
2h = r-h
3h = r
h = r / 3
