Answer:
4 m/s
Explanation:
m1 = m2 = m
u1 = 20 m/s, u2 = - 12 m/s
Let the speed of composite body is v after the collision.
Use the conservation of momentum
Momentum before collision = momentum after collision
m1 x u1 + m2 x u2 = (m1 + m2) x v
m x 20 - m x 12 = (m + m) x v
20 - 12 = 2 v
8 = 2 v
v = 4 m/s
Thus, the speed of teh composite body is 4 m/s.
Answer:
K = 373.13 N/m
Explanation:
The force of the spring is equals to:
Fe - m*g = 0 => Fe = m*g
Using Hook's law:
K*X = m*g Solving for K:
K = m/X * g
In this equation, m/X is the inverse of the given slope. So, using this value we can calculate the spring's constant:
K = 10 / 0.0268 = 373.13N/m
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Incomplete question. Missing part:
"it took him 10 seconds to move the couch. What was his power?"
Answer:
50 W
Explanation:
The power developed is given by:

where
W is the work done
t is the time taken
In this problem,
W = 500 J
t = 10.0 s
Substituting into the equation, we find

Answer:
Car has more power output than crane
Explanation:
We have given that mass of the crane m = 1000 kg
Height through which crane lift the steel beam h = 10 m
Acceleration due to gravity 
So work done by crane 
Time period is given as t = 5 sec
We know that power 
Now mass of the car = 1000 kg
Initial velocity u = 0 m /sec
Final velocity v = 10 m/sec
We know that work done is equal to the change in kinetic energy
So work done 

Time ids given as t = 2 sec
So power 
So car has more power output than crane