Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?
1 answer:
Answer:
D) Both do zero work
Explanation:
The work done by a force is given by:
where
F is the force applied
d is the displacement
is the angle between the direction of the force and the displacement
From the formula, we notice that work is done online when the displacement is non-zero, so when the object is moving.
In this problem, the wall is stationary: this means that the displacement is zero, d = 0, so no work is done.
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Answer:
The decelerating force is
Solution:
As per the question:
Frontal Area, A =
Speed of the spaceship, v =
Mass density of dust,
Now, to calculate the average decelerating force exerted by the particle:
(1)
Volume,
Thus substituting the value of volume, V in eqn (1):
where
A = Area
v = velocity
t = time
(2)
From Newton's second law of motion:
Thus differentiating w.r.t time 't':
where
= average decelerating force of the particle
Now, substituting suitable values in the above eqn: