The correct option is A) work.
Work is said to be done by a force when a force is exerted on an object and the the object on which the force is exerted moves in the direction of the force.
The amount of work done is given by the product of the force and the displacement made by the object.
Option (B) is incorrect, since Watt is the unit of power.
Option (C) is wrong, since joule is the unit of work or energy.
Option (D) is wrong, since power is the rate at which work is done.
Explanation:
Let
= distance traveled while accelerating
= distance traveled while decelerating
The distance traveled while accelerating is given by
We need the velocity of the rocket after 30 seconds and we can calculate it as follows:
This will be the initial velocity when start calculating for the distance it traveled while decelerating.
Solving for we get
Therefore, the total distance x is
Answer:
10 days
Explanation:
The half-life of a radioactive sample is the time taken for half of the sample to decay.
In the diagram, the half-life corresponds to the time after which the % of cobalt-57 has halved. We can observe the following:
At t=10 days, the % of Co remaining is approximately 45%
At t=20 days, the % of Co remaining is approximately 22%
This means that the sample of cobalt-57 has halved in 10 days, so the half-life of cobalt-57 is 10 days.
Answer:
a = 5 [m/s²].
Explanation:
To solve this equation we must use the following equation of kinematics.
where:
Vf = final velocity = 25 [m/s]
Vo = initial velocity = 5 [m/s]
a = acceleration [m/s²]
t = time = 4 [s]
Note: The positive sign for the acceleration in the above equation means that the car is increasing its velocity.
25 = 5 +a*(4)
25 - 5 = 4*a
20 = 4*a
a = 5 [m/s²]