Answer:
Minimum work = 5060 J
Explanation:
Given:
Mass of the bucket (m) = 20.0 kg
Initial speed of the bucket (u) = 0 m/s
Final speed of the bucket (v) = 4.0 m/s
Displacement of the bucket (h) = 25.0 m
Let 'W' be the work done by the worker in lifting the bucket.
So, we know from work-energy theorem that, work done by a force is equal to the change in the mechanical energy of the system.
Change in mechanical energy is equal to the sum of change in potential energy and kinetic energy. Therefore,

Therefore, the work done by the worker in lifting the bucket is given as:

Now, plug in the values given and solve for 'W'. This gives,

Therefore, the minimum work that the worker did in lifting the bucket is 5060 J.
Basically, when someone is resting in an accelerated vehicle without restraint from a seatbelt, the force of stopping the vehicle will be when inertia occurs, and that force of the vehicle coming to a stop will affect the passenger (without a seatbelt/restraint from another force or object) greatly by throwing them.
For example;
If I were to be riding in a vehicle (without a seatbelt) that's accelerating at 40 m/s^2 and it suddenly gets slammed on the breaks, I will be thrown forward from inside the vehicle.
I hope this helps!
Answer:
(a)
(b) It won't hit
(c) 110 m
Explanation:
(a) the car velocity is the initial velocity (at rest so 0) plus product of acceleration and time t1

(b) The velocity of the car before the driver begins braking is

The driver brakes hard and come to rest for t2 = 5s. This means the deceleration of the driver during braking process is

We can use the following equation of motion to calculate how far the car has travel since braking to stop


Also the distance from start to where the driver starts braking is

So the total distance from rest to stop is 352 + 88 = 440 m < 550 m so the car won't hit the limb
(c) The distance from the limb to where the car stops is 550 - 440 = 110 m
Direction of resultant force in circular motion is directed towards the center of the circle. Hence vector B is the direction of the resultant force.