A weightlifter lifts a 1250-N barbell 2 m in 3 s.How much power was used to lift the barbell?
1 answer:
The power is 833.3 W
Explanation:
First of all, we need to calculate the work done in lifting the barbell, which is equal to the change in gravitational potential energy of the barbell:
where
mg = 1250 N is the weight of the barbell
h = 2 m is the change in height
Substituting,
Now we can calculate the power, which is equal to the work done per unit time:
where
W = 2500 J is the work done
t = 3 s is the time taken
Substituting,
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The speed of the ball is B. 5 meters per second
Explanation:
For an object in uniform motion (= at constant velocity), the speed can be calculated using the equation
where
v is the speed
d is the distance covered
t is the time taken
For the ball in this problem:
d = 50 m is the distance covered
t = 10 s is the time taken
Substituting, we find the speed:
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To solve this problem we use the general kinetic equations.
We need to know the time it takes for the car to reach 130 meters.
In this way we have to:
Where
= initial position
= initial velocity
= acceleration
= time
= position as a function of time
.
We use the quadratic formula to solve the equation.
t = 6.63 s and t = -17.1 s
We take the positive solution. This means that the car takes 6.63 s to reach 130 meters.
Then we use the following equation to find the final velocity:
Where:
= final speed
The final speed of the car is 27.25 m/s
The height, h to which the package of mass m bounces to depends on its initial velocity, v and the acceleration due to gravity, g and is given below:
Perfectly elastic collisions are collisions in which the momentum as well as the energy of the colliding bodies is conserved.
In perfectly elastic collisions, the sum of momentum before collision is equal to the momentum after collision.
Also, the sum of kinetic energy before collision is equal to the sum of kinetic energy after collision.
Since some of the Kinetic energy is converted to potential energy of the body;
Therefore, the height to which the package m bounces to depends on its initial velocity and the acceleration due to gravity.
Learn more about elastic collisions at: brainly.com/question/7694106