Answer:
The value of d is 20.4 m.
(C) is correct option.
Explanation:
Given that,
Initial velocity = 20 m/s
Final velocity = 0
We need to calculate the time
Using equation of motion

Where, u = Initial velocity
v = Final velocity
Put the value into the formula


We need to calculate the distance
Using equation of motion



Hence, The value of d is 20.4 m.
Answer:
Approximately
.
Assumption: the ball dropped with no initial velocity, and that the air resistance on this ball is negligible.
Explanation:
Assume the air resistance on the ball is negligible. Because of gravity, the ball should accelerate downwards at a constant
near the surface of the earth.
For an object that is accelerating constantly,
,
where
is the initial velocity of the object,
is the final velocity of the object.
is its acceleration, and
is its displacement.
In this case,
is the same as the change in the ball's height:
. By assumption, this ball was dropped with no initial velocity. As a result,
. Since the ball is accelerating due to gravity,
.
.
In this case,
would be the velocity of the ball just before it hits the ground. Solve for
.
.
Answer:
Net force on the block is 32 N.
Acceleration of the object is 6.4 m/s².
Explanation:
Let the acceleration of the object be
m/s².
Given:
Mass of the block is, 
Force of pull is, 
Frictional force on the block is, 
The free body diagram of the object is shown below.
From the figure, the net force in the forward direction is given as:

Now, from Newton's second law of motion, net force is equal to the product of mass and acceleration. So,

Therefore, the acceleration of the object in the forward direction is 6.4 m/s².
Answer:
(a) The announcer's claim is incorrect because the divers enter at a speed of 20.4 and not 25 m/s as announced
(b) it’s possible for a diver to enter the water with the velocity of 25 m/s if he has initial velocity of 14.4 m/s. The upward initial velocity can’t be physically attained
Explanation:
(a)
To find the final velocity
for an object traveling distance h taking the initial vertical component of velocity as
the kinematics equation is written as
where a is acceleration
Substituting g for a where g is gravitational force value taken as 9.81

Since the initial velocity is zero, we can solve for final velocity by substituting figures, note that 70 ft is 21.3 m for h
= 20.44275
Therefore, the divers enter with a speed of 20.4 m/s
The announcer's claim is incorrect because the divers enter at a speed of 20.4 and not 25 m/s as announced
(b)
The divers can enter water with a velocity of 25 m/s only if they have some initial velocity. Using the kinematic equation

Since we have final velocity of 25 m/s


= 14.390761 m/s
Therefore, it’s possible for a diver to enter the water with the velocity of 25 m/5 if he has initial velocity of 14.4 m/s
In conclusion, the upward initial velocity can’t be physically attained