Kinematics: Solving Questions on Speed, Distance, Time & Acceleration

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In summary, the first conversation involved a stone being thrown vertically upward from the edge of a cliff with a speed of 11.0 m/s. The questions asked included how long it takes to reach the bottom of the cliff, what the speed is just before hitting, and the total distance traveled. The second conversation involved a car rolling off a vertical cliff and the time it takes to reach a speed of 74 km/h. The final conversation involved a sports car accelerating from rest to 99 km/h in 6.2 seconds and finding its average acceleration in m/s2.
  • #1
jimlee4262
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1.A stone is thrown vertically upward with a speed of 11.0 m/s from the edge of a cliff 79.0 m high (Fig. 2-32).

(a) How much later does it reach the bottom of the cliff?

(b) What is its speed just before hitting?

(c) What total distance did it travel?

2.If a car rolls gently (v0 = 0) off a vertical cliff, how long does it take it to reach 74 km/h?

3.A sports car accelerates from rest to 99 km/h in 6.2 s. What is its average acceleration in m/s2?
 
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  • #2
Most of these can be solved once you set up an equation of motion representing your situation.

I suggest you make an attempt :eek:
 
  • #3
yes i figured out the last two but the first one i am having trouble on... I found most of the missing variable but i can't seem to get the ones i need right.
 
  • #4
the answers i have gotten for the first one is
A) 5.12
B)-39.3
C)-91.3
Can someone tell me if i did this wrong and help me
 
  • #5
jimlee4262 said:
the answers i have gotten for the first one is
A) 5.12
B)-39.3
C)-91.3
Can someone tell me if i did this wrong and help me

a) 0.13424051
b)588.495976
s)79.0
 
  • #6
the pro said:
a) 0.13424051
b)588.495976
s)79.0

a) 0.13424051s doesn't leave much time to reach the maximum height and then fall 79m plus the additional height achieved by the 11.0m/s initial velocity.
b) Accelerating to 588.495976m/s in 0.13424051s would require that acceleration due to the force of gravity is 4380.1979 m/s2
c) What about the distance upward due to the initial velocity of 11.0m/s?
 
  • #7
I came up with
a) 5.29 s
b) 40.9 m/s (the problem asks for speed, which is the absolute value of velocity)
c) 91.4 m
 

1. What is kinematics?

Kinematics is the branch of physics that studies the motion of objects without considering the forces that cause the motion.

2. What is the difference between speed and velocity?

Speed is the rate at which an object moves, while velocity is the rate at which an object moves in a specific direction. Velocity takes into account both speed and direction, while speed only considers the magnitude of the movement.

3. How do you calculate average speed?

Average speed is calculated by dividing the total distance traveled by the total time taken. For example, if a car travels 100 miles in 2 hours, the average speed would be 50 miles per hour.

4. What is the formula for calculating acceleration?

The formula for acceleration is a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

5. How can you use kinematics equations to solve real-world problems?

Kinematics equations can be used to solve real-world problems by providing a mathematical framework for understanding and predicting the motion of objects. By using these equations, scientists and engineers can design and improve technologies that involve movement, such as cars, airplanes, and rockets.

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