C
The potential energy is mgh, she knows the mass, she needs the acceleration due to gravity and the height of the ball
(a) 154.5 N
Let's divide the motion of the sprinter in two parts:
- In the first part, he starts with velocity u = 0 and accelerates with constant acceleration for a total time During this part of the motion, he covers a distance equal to , until he finally reaches a velocity of . We can use the following suvat equation:
which reduces to
(1)
since u = 0.
- In the second part, he continues with constant speed , covering a distance of in a time . This part of the motion is a uniform motion, so we can use the equation
(2)
We also know that the total time is 10.0 s, so
Therefore substituting into the 2nd equation
From eq.(1) we find
(3)
And substituting into (2)
Solving for t,
So from (3) we find the acceleration in the first phase:
And so the average force exerted on the sprinter is
b) 14.5 m/s
The speed of the sprinter remains constant during the last 55 m of motion, so we can just use the suvat equation
where we have
u = 0
is the acceleration
is the time of the first part
Solving the equation,
Answer:
145 m
Explanation:
Given:
Wavelength (λ) = 2.9 m
we know,
c = f × λ
where,
c = speed of light ; 3.0 x 10⁸ m/s
f = frequency
thus,
substituting the values in the equation we get,
f = 1.03 x 10⁸Hz
Now,
The time period (T) =
or
T = = 9.6 x 10⁻⁹ seconds
thus,
the time interval of one pulse = 100T = 9.6 x 10⁻⁷ s
Time between pulses = (100T×10) = 9.6 x 10⁻⁶ s
Now,
For radar to detect the object the pulse must hit the object and come back to the detector.
Hence, the shortest distance will be half the distance travelled by the pulse back and forth.
Distance = speed × time = 3 x 10^8 m/s × 9.6 x 10⁻⁷ s) = 290 m {Back and forth}
Thus, the minimum distance to target = = 145 m
Answer:
position 2
Explanation:
the gravity from the ball to the floor had the most movement involved.