Den pushes a desk 400 cm across the floor. He exerts a force of 10 N for 8 s to move the desk. What is his power output? (Power:
P = W/t) 1.25 W 5 W 40 W 500 W
1 answer:
Answer:
5 W
Explanation:
The formula of the power is:
● P = W/t
W is the work and t is the time needed to do it(in seconds)
Let's calculate first the work that the force exerced:
W = Vector F . Vector d
D is the distance ( here 400 cm wich is 4 m)
Make a representation to see how are the vectors F and V.(picture below)
The vector F and d are colinear since Den is pushing the desk on the ground.
● W = 4 × 10 = 40 J
J is Joule
■■■■■■■■■■■■■■■■■■■■■■■■■■
● P = W / t
● P = 40/ 8
● P = 5 W
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Answer:
F = 4000 N
Explanation:
given,
mass of rocket (M)= 5000 Kg
10 Kg gas burns at speed (m)= 4000 m/s
time = 10 s
average force = ?
at the end the rocket is at rest
by conservation of momentum
M v + m v' = 0
5000 x v - 10 x 4000 = 0
5000 v = 40000
v = 8 m/s
speed of rocket = 8 m/s
now,
we know
change in momentum = F x Δ t
F = 4000 N
Hence, the average force applied to the rocket is equal to F = 4000 N