Answer:
Power rating on the blender = 3809.52 Watts
Explanation:
We have expression for power equal to ratio of work and time,
Energy used by blender = Work done by electricity = 0.8 MJ =
Time of using blender = 3.5 minutes = 210 seconds
So power of blender = 800000/210 = 3809.52 Watts
Power rating on the blender = 3809.52 Watts
Answer:
Ideally, the work output of a lever should match the work input. However, because of resistance, the output power is nearly always be less than the input power. As a result, the efficiency would go below .
Explanation:
In an ideal lever, the size of the input and output are inversely proportional to the distances between these two forces and the fulcrum. Let and
denote these two distances, and let
and
denote the input and the output forces. If the lever is indeed idea, then:
.
Rearrange to obtain:
Class two levers are levers where the perpendicular distance between the fulcrum and the input is greater than that between the fulcrum and the output. For this ideal lever, that means , such that
.
Despite , the amount of work required will stay the same. Let
denote the required linear displacement for the output force. At a distance of
from the fulcrum, the angular displacement of the output force would be
. Let
denote the corresponding linear displacement required for the input force. Similarly, the angular displacement of the input force would be
. Because both the input and the output are on the same lever, their angular displacement should be the same:
.
Rearrange to obtain:
.
While increasing reduce the size of the input force
, doing so would also increase the linear distance of the input force
. In other words,
will have to move across a longer linear distance in order to move
by the same
.
The amount of work required depends on both the size of the force and the distance traveled. Let and
denote the input and output work. For this ideal lever:
.
In other words, the work input of the ideal lever is equal to the work output.
The efficiency of a machine can be measured as the percentage of work input that is converted to useful output. For this ideal lever, that ratio would be - not anything higher than that.
On the other hand, non-ideal levers take in more work than they give out. The reason is that because of resistance, would be larger than ideal:
.
As a result, in real (i.e., non-ideal) levers, the work input will exceed the useful work output. The efficiency will go below ,
a) 779 kg m/s
The momentum of an object is given by:
p = mv
where
m is the mass of the object
v is its velocity
For the fullback before the collision,
m = 95 kg
v = 8.2 m/s
Therefore, his momentum was:
b) -779 kg m/s
After the collision, both the fullback and the tackle come to a stop: this means that their momentum after the collision is zero,
p' = 0
The initial momentum of the fullback was
p = 779 kg m/s
Therefore, his change in momentum is
where the negative sign indicates that the direction is opposite to the initial direction of motion.
c) -779 kg m/s
Here we can apply the law of conservation of momentum. In fact, the total momentum before and after the collision must be conserved. So we can write:
where
is the initial momentum of the fullback
is the initial momentum of the tackle
p' is the final combined momentum after the collision
We already know that
Therefore, we can find the tackle's original momentum:
where the negative sign indicates that the direction is opposite to the initial direction of motion of the fullback.
e) -6.1 m/s
To find the velocity of the tackle, we can use again the equation of the momentum:
p = mv
where here we have
is the original momentum of the tackle
m = 128 kg is his mass
Solving the equation for v, we find the tackle's original velocity:
So, he was moving at 6.1 m/s in the direction opposite to the fullback.