Average speed = (distance covered) / (time to cover the distance)
= (20 miles) / (45 minutes)
Multiply that fraction by (60 minutes / 1 hour) .
This is equal to ' 1 ', so you won't change anything except the units.
= (20 miles / 45 minutes) times (60 minutes / 1 hour)
Multiply the fractions, then cancel 'minutes' out of
the numerator and denominator.
= (20 miles x 60) / (45 x 1 hour)
= (20 x 60 / 45) miles/hour
= 26-2/3 miles/hour .
Answer:
-1.67 m/s
Explanation:
We can solve this problem by using the law of conservation of momentum: in fact, since the system is isolated (no external forces, since the ice is frictionless), the total momentum of Evelyin and Lily must be conserved.
The total momentum before is zero, since they are both at rest:
The total momentum after is:
where
m = 48.3 kg is Lily's mass
M = 57.4 kg is Evelyin's mass
V = 1.4 m/s is Evelyn's velocity
v is the Lily's velocity
Since momentum is conserved,
And so
Solving for v, we find Lily's velocity:
And the negative sign indicates that her direction is opposite to Evelyn's direction.
First, we need to fight the weight of the balls instead of their mass. We do this by multiplying their weight it kg by 9.8. This gives us .98 N. To find the potential energy of the rolling ball, we find its kinetic energy. The formula for this is KE=mass*velocity^2*1/2.
Plugging in our numbers, we have Kinetic energy = .1 * 1^2*1/2 which gives us .05 joules.
Now we find the potential energy of the ball on the shelf. For this we do:
Potential energy = .1*9.8*1, and our answer is .98 joules. Clearly, the ball on the shelf has more energy.
Answer:
The efficiency is just 0.016
Explanation:
The efficiency is given by the useful energy ÷ by the total energy.
1 W is the same that 1 joule per second
If you do the math:
1.6/100=0.016