Answer: 7291.2 joules
Explanation:
Work is done when force is applied on an object over a distance.
Thus, Workdone = Force X distance
Since Distance moved by box = 12 metres
mass of box = 62kg
Acceleration due to gravity when box was lifted is represented by g = 9.8m/s^2
Recall that Force = Mass x acceleration due to gravity
i.e Force = 62kg x 9.8m/s^2
= 607.6 Newton
So, Workdone = Force X Distance
Workdone = 607.6 Newton X 12 metres
Workdone = 7291.2 joules
Thus, 7291.2 joules of work was done.
Answer:C
Explanation: I studied, and C is correct
Answer:
I don't know sorry For this question
Answer:
The car stops in 7.78s and does not spare the child.
Explanation:
In order to know if the car stops before the distance to the child, you take into account the following equation:
(1)
vo: initial speed of the car = 45km/h
a: deceleration of the car = 2 m/s^2
t: time
xo: initial distance to the child = 25m
x: final distance to the child = 0m
It is necessary that the solution of the equation (1) for time t are real.
You first convert the initial speed to m/s, then replace the values of the parameters and solve the quadratic polynomial for t:
You take the first value t1 because it has physical meaning.
The solution for t is real, then, the car stops in 7.78s and does not spare the child.
Answer:
Explanation:
A )
speed of swimming in still water is given by the expression
distance / time
= 50 / 25
= 2 m /s
In lane 1 , 1.2 cm/s current is flowing in the direction that the swimmers are going so swimmers will cover distance at the rate of 2 + 1.2 = 3.2 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / 3.2 = 15.625 s
In lane 8 , 1.2 cm/s current is flowing against the direction that the swimmers are going so swimmers will cover distance at the rate of 2 - 1.2 = .8 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / .8 = 62.5 s
