Answer:
<h3>a. mgh</h3>
Explanation
The work done by the lifter is equal to its potential energy since he is covering a height and under the influence of gravity.
potential energy = mass * acceleration due to gravity * height
m is the mass
g is the acceleration due to gravity
h is the height
Hence the required workdone = PE = mgh
3 km in 20 min => 9 km in 60 min => 9km in 1h =>
the correct answer is d: 9 km/h
I can help you with 5. 5 is a displacement-time graph.
At A it is moving in a positive direction and speed is constant.
At B it is stationary or at rest.
At C, movement is negative and it is decreasing or decelerating
At D, it’s a general downwards movement in the negative direction that can be described as overall constant
