i need to construct a device that minimizes heat transfer so that i can keep an ice cube anew ice cube for a long period of time
2 answers:
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Answer:
Assumption: the air resistance on this ball is negligible. Take .
a. The momentum of the ball would be approximately two seconds after it is tossed into the air.
b. The momentum of the ball would be approximately three seconds after it reaches the highest point (assuming that it didn't hit the ground.) This momentum is smaller than zero because it points downwards.
Explanation:
The momentum of an object is equal its mass
times its velocity
. That is:
.
Assume that the air resistance on this ball is negligible. If that's the case, then the ball would accelerate downwards towards the ground at a constant . In other words, its velocity would become approximately
more negative every second.
The initial velocity of the ball is . After two seconds, its velocity would have become
. The momentum of the ball at that time would be around
.
When the ball is at the highest point of its trajectory, the velocity of the ball would be zero. However, the ball would continue to accelerate downwards towards the ground at a constant . That's how the ball's velocity becomes negative.
After three more seconds, the velocity of the ball would be . Accordingly, the ball's momentum at that moment would be
.
Answer:
7.5 km/h (2.1 m/s) due east
Explanation:
The average velocity of the person is given by:
where
d is the displacement
t is the time taken
In this problem,
d = 15 km is the displacement
t = 2.0 h is the time elapsed
so the average velocity is
and the direction is the same as the displacement (east).
We can also convert the velocity into SI units (m/s). We have:
d = 15 km = 15,000 m
t = 2.0 h * 3600 s/h = 7200 s