(a) Calculate the work done on a 1500-kg elevator car by its cable to lift it 40.0 m at constant speed, assuming friction averag
1 answer:
Answer:592 kJ
Explanation:
Given
mass of elevator m=1500 kg
Lifting height=40 m
Friction Force F=100 N
The cable has to work against gravitational force and friction Force
Increase in Potential Energy of Elevator
thus work done by gravitational force
Work done against friction force
Total Work done by the cable
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Answer:
J = 12.32kg*m/s
Explanation:
Assumptions: I'm assuming mis is m/s
Given: The baseball's mass is 140g, so convert to kg, 0.140kg. (Good rule of thumb, in physics convert grams to kilograms). It is initially traveling 35 m/s to the right.
When it hits the bat, it flies left with a velocity of 55 m/s at an angle of 25°. To reiterate:
mass = 0.140kg, Initial: 35m/s, Final: 55m/s at an angle of 25°
For this problem, we have to use the impulse equation, but before that lets break the velocity into components (It will be apparent towards the end):
The initial velocity is moving only in the horizontal direction, so:
The final velocity has an x and a y component:
Now the equation for impulse is (dp is Δp, which is difference in momentum; dv is Δv, the difference in velocity; J is impulse):
To get Δv, we have to find the difference of velocity, that is why we broke it into components. I'm going to define right as positive and left as negative. After that, we find the velocity vector:
Finally, substitute into the equation
J = 12.32kg*m/s