1) a water balloon is thrown toward a target at 18 m/s. If the water balloon has a mass of 0.4 kg, what is its momentum?
A) 7.2 kg • m/s
B) 18.4 kg • m/s
C) 45 kg • m/s
D) 7.2 kg • m
2) what is the momentum of a car with a mass of 2,000 kg moving at a constant velocity of 20 m/s
A) 0 kg • m/s
B) 100 kg • m/s
C) 40,000 kg • m/s
D) 0.01 kg • m/s
3) if an astronaut in space pushes off the satellite she is working on, what will happen to her if there are no other acting external forces?
A) she will eventually slow down and come to a stop
B) she will continuously speed up
C) she will periodically change direction
D) she will move in the same direction at the same speed
4) An ice skater at rest on ice catches a dance partner moving 2.5 m/s during a performance. The ice skater has a mass of 68 kg and the dance partner has a mass of 54 kg. What is the speed of the ice skater and dance partner after the collision?
A) 2.3 m/s
B) 2.0 m/s
C) 1.4 m/s
D) 1.1 m/s
5) A machine works with an efficiency of 18%. The energy input is 500 joules/second. How much useful energy will the machine generate in 15 minutes?
A) 81 kJ
B) 1.35 kJ
C) 25 kJ
D) 135 kJ
6) a lever is being used to try to lift a heavy object, but it is not working. Which of these actions would increase the output force the most?
A) decrease the input force and increase the output displacement
B) increase the input force and decrease the output displacement
C) decrease the input force and decrease the output displacement
D) increase the input force and increase the output displacement
7) a box with a weight of 50 newtons is pushed with a force of 20 newtons along an inclined plane that is 10 meters long up to the top of a ramp. What is the height of the ramp?
A) 2.5 m
B) 200 m
C) 4 m
D) 25 m
anonymous you're kinda a buzz kill
did u find the answers ??
To find the momentum, we use the formula:
momentum = mass × velocity
1) The mass of the water balloon is given as 0.4 kg and the velocity as 18 m/s.
So, momentum = 0.4 kg × 18 m/s = 7.2 kg · m/s
Therefore, the correct answer is A) 7.2 kg · m/s.
2) The mass of the car is given as 2,000 kg and the velocity as 20 m/s.
So, momentum = 2,000 kg × 20 m/s = 40,000 kg · m/s
Therefore, the correct answer is C) 40,000 kg · m/s.
3) According to Newton's third law of motion, every action has an equal and opposite reaction. When the astronaut pushes off the satellite, she exerts a force on the satellite, and the satellite exerts an equal and opposite force on her. Thus, she will move in the opposite direction to the satellite and with the same speed (by the conservation of momentum), unless acted upon by other external forces.
Therefore, the correct answer is D) she will move in the same direction at the same speed.
4) In this scenario, we can use the principle of conservation of momentum:
Initial momentum = Final momentum
The initial momentum is the sum of the momentum of the ice skater and the momentum of the dance partner. The ice skater is at rest initially, so their momentum is zero.
Given: Mass of the ice skater = 68 kg, Velocity of the dance partner = 2.5 m/s, Mass of the dance partner = 54 kg
Final momentum = 0 + (Mass of the dance partner × final velocity)
Let final velocity be v.
Final momentum = 54 kg × v
Equating initial and final momentum:
0 = 54 kg × v
Therefore, v = 0 m/s
So, the speed of the ice skater and the dance partner after the collision is 0 m/s.
Therefore, the correct answer is D) 1.1 m/s.
5) Efficiency is given as the ratio of useful work output to the total work input.
Efficiency = (Useful energy output / Energy input) × 100%
Given: Efficiency = 18%, Energy input = 500 joules/second
We need to find the useful energy output in 15 minutes. First, we convert 15 minutes to seconds:
15 minutes = 15 × 60 seconds = 900 seconds
Now, we can calculate the useful energy:
Useful energy output = Efficiency × Energy input × Time
= 0.18 × 500 joules/second × 900 seconds
= 81,000 joules
Converting joules to kilojoules:
81,000 joules = 81 kilojoules
Therefore, the correct answer is A) 81 kJ.
6) In this scenario, we can use the principle of the lever: input force × input displacement = output force × output displacement.
To increase the output force the most, we need to increase the input force and increase the output displacement. So the correct answer is D) increase the input force and increase the output displacement.
7) To find the height of the ramp, we can use the concept of work: work = force × distance.
Given: Weight of the box = 50 N, Force applied = 20 N, Length of the inclined plane = 10 m.
The work done by the force applied must be equal to the gravitational potential energy gained by the box.
Gravitational potential energy = weight × height
Work done = Force × distance
Gravitational potential energy = Work done
= Force × distance
50 N × height = 20 N × 10 m
50N × height = 200 N·m
height = (200 N·m) / 50 N
height = 4 m
Therefore, the correct answer is C) 4 m.
1)a, 2)c ,3)d ,4)d, 5)a, 6)b, 7)c
You sure do.
I am not going to do these for you.
1.momentum , P = m v
2. same
3. TOTAL momentum the same before and after. She goes one way, the sat the other
4. conservation of momentum again
5. 0.18*500 * 15 * 60
6. oh come on !
7. m g h = work in = 20 * 10, note m g = 50 N