1.A race car has a mass of 707 kg. It starts from rest and travels 42.0 m in 3.0 s. The car is uniformly accelerated during the entire time. What net force is exerted on it?
2.A 4430 kg helicopter accelerates upward at 2.2 m/s2. What lift force is exerted by the air on the propellers?
3.A dragster starts with zero velocity and completes a 404.8 m (0.2530 mile) run in 4.915 s. If the car had a constant acceleration, what would be its acceleration and final velocity?
4.Suppose 70 kg boy and a 50 kg girl use a massless rope in a tug-of-war on an icy, resistance-free surface, as in figure 4-21. If the acceleration of the girl toward the boy is 3.0 m/s2, find the magnitude of the acceleration of the boy toward the girl.
5.On Earth, a scale shows that you weigh 645 N.
What is your mass?
What would the scale read on the moon (g = 1.60 m/s2)?
I will be happy to critique your thinking on these.
a motorcycle accelerates uniformly from rest reaching a speed of 200 mi/hr in 10seconds whats is the acceleration
1. To find the net force exerted on the race car, we can use Newton's second law of motion, which states that the net force acting on an object is equal to the product of its mass and acceleration.
The given information includes the mass of the race car (707 kg) and the time taken to travel a certain distance (3.0 s). Since the car starts from rest, its initial velocity is zero.
We can calculate the acceleration using the formula:
acceleration = (final velocity - initial velocity) / time
Since the initial velocity is zero, the formula simplifies to:
acceleration = final velocity / time
The final velocity can be calculated using the formula:
final velocity = (initial velocity) + (acceleration * time)
Substituting the values, we get:
final velocity = (0) + (acceleration * 3.0)
Since the car travels a distance of 42.0 m, we can calculate the final velocity using the formula:
final velocity^2 = (initial velocity)^2 + (2 * acceleration * distance)
Substituting the values, we get:
velocity^2 = (0)^2 + (2 * acceleration * 42.0)
Simplifying further, we have:
velocity^2 = 84 * acceleration
Now we have two equations, one for acceleration and one for final velocity. We can solve the system of equations to find the values.
Once we find the acceleration, we can calculate the net force using Newton's second law:
net force = mass * acceleration
2. To find the lift force exerted by the air on the helicopter's propellers, we can use Newton's second law of motion.
The given information includes the mass of the helicopter (4430 kg) and the acceleration it experiences (2.2 m/s^2) in the upward direction.
Using Newton's second law:
net force = mass * acceleration
The lift force is equal to the net force in the upward direction.
3. To find the acceleration and final velocity of the dragster, we can use the equations of motion.
The given information includes the distance traveled (404.8 m) and the time taken (4.915 s). The initial velocity is zero since the dragster starts from rest.
We can calculate the acceleration using the formula:
acceleration = 2 * (distance - (initial velocity * time)) / (time^2)
Substituting the values, we get:
acceleration = 2 * (404.8 - (0 * 4.915)) / (4.915^2)
Once we find the acceleration, we can use the formula:
final velocity = initial velocity + (acceleration * time)
Since the initial velocity is zero, the final velocity simplifies to:
final velocity = acceleration * time
4. To find the magnitude of the acceleration of the boy toward the girl, we need to use Newton's second law of motion.
The given information includes the mass of the boy (70 kg) and the mass of the girl (50 kg). We are also given the acceleration of the girl toward the boy (3.0 m/s^2).
According to Newton's third law of motion, the force exerted on the girl by the boy is equal in magnitude and opposite in direction to the force exerted on the boy by the girl.
Using Newton's second law:
force = mass * acceleration
The force exerted on the boy is equal to the product of the boy's mass and his acceleration, which we need to find.
5. To find your mass, we can use the formula:
weight = mass * gravitational acceleration
The weight on Earth is given as 645 N, and the gravitational acceleration on Earth is approximately 9.8 m/s^2.
Substituting the values, we get:
645 = mass * 9.8
To find the mass, divide both sides of the equation by 9.8:
mass = 645 / 9.8
To find what the scale would read on the moon, we need to use the formula:
weight = mass * gravitational acceleration
The gravitational acceleration on the moon is given as 1.6 m/s^2.
Substituting the values, we get:
weight = mass * 1.6
To find the weight on the moon, divide both sides of the equation by 1.6:
weight/1.6 = mass
This will give you the value that the scale would read on the moon.