Answer:
12500W
Explanation:
Given parameters:
Work done = 250000J
Time taken = 20s
Unknown:
Power of the crane = ?
Solution:
Power is the defined as the rate at which work is being done;
Mathematically;
Power = 
insert the parameters and solve;
Power = 
= 12500W
Answer:
45 s .
Explanation:
The accelerator will first accelerate , then move with uniform velocity and at last it will decelerate to rest .
displacement s = ?
acceleration a = 1 m /s²
Final speed v = 5 m/s
initial speed u = 0
v² = u² + 2as
5² = 0 + 2 x 1 x s
s = 12.5 m
B) Let time of acceleration or deceleration be t
v = u + a t
5 = 0 + 1 t
t = 5 s
Similarly displacement during deceleration = 12.5 m
Total distance during uniform motion = 200 - ( 12.5 + 12.5 ) = 175 m .
velocity of uniform motion = 5 m /s
time during which there was uniform velocity = 175 / 5 = 35 s
Total time = 5 + 35 + 5 = 45 s .
Average speed= total distance/total time =12km/h
Answer:
v'=5.97 m/s
Explanation:
If the friction and fluid friction are ignored, then by law of conservation of mechanical energy, potential energy at the top of the slide must be equal to the kinetic energy at the bottom of the slide. Thus, the height of slide and final speed at the bottom of the slide are related as:
let the final speed be v' when h' = 2 h
Answer:
Since the astronaut drops the rock, the initial velocity of the rock is 0 m/s
<u>We are given:</u>
initial velocity (u) = 0 m/s
final velocity (v) = v m/s
acceleration (a) = 1.62 m/s/s
height (h) = 1.25 m
<u>Solving for v:</u>
From the third equation of motion:
v²-u² = 2ah
replacing the variables
v² - (0)² =2 (1.62)(1.25)
v² = 1.62 * 2.5
v² = 4 (approx)
v = √4
v = 2 m/s
The speed of the rock just before it lands is 2 m/s
