Out of that list, the concave mirror is the only item that can concentrate sunlight and heat into a small area. But if you could get ahold of a convex lens, that would be even better.
Answer:
Different street blocks are different lengths, so it won't be possible to answer this.
<span>As time increases, if the particle's velocity changes sign from positive to negative, or negative to positive, then it must have changed (opposite) direction on its linear path. As time increases on a graph of the particle's position versus time, it changes directions when position changes from increasing to decreasing, or from decreasing to increasing.</span>
Speed is scalar, meaning it's only going to be like 74 mph, doesn't matter which direction. Velocity is a vector, meaning it has direction. You can go -74mph when talking about velocity, not speed.
Answer:
You need to trust your instinct and if you think its going to get you injured, don't do it.
