Answer:
D (not so sure, look in the explanation and judge yourself)
Explanation:
Assume that the acceleration due to gravity is 9.81 m/s^2 downwards
Minimum force required = 0.25 x 34 x 9.81
= 83.385 N
So technically the force need to be greater than 83.385 so the answer should be d, not really sure if it should be b though really depends on the acceleration due to gravity.
I think your answer would be C. because they are replacing the trees they are cutting down.
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
Since 1m/s=3.6 km/h, we can conclude that 10.0m/s = 36 km/h