Answer:
4.0 m/s
Explanation:
In the first part of the run, the athlete runs a distance of
at a speed of
So, the time he/she takes is
In the second part of the run, the athlete covers an additional distance of
with a speed
So, the time taken in this second part is
So, the total distance covered is
d = 300 m + 300 m = 600 m
And the total time taken
t = 100 s + 50 s = 150 s
Therefore, the average speed for the entire trip is
Answer:
B
Explanation:
Solution:-
- Take a coordinate system as follows:
x: Directed along the ground
y: Directed vertical to ground
- We will assume that the initial vertical and horizontal non-zeroes velocities are given as follows:
- After a ball is thrown it continues a path of parabolic projectile. The motion of the ball can be analyzed in each coordinate system. We will assume that effects of air-resistance are negligible.
- Therefore, only gravity acts on the ball in the vertical direction. We can use kinematic equation of motions to determine the velocity of ball in either ( x-y ) direction at any instant of time ( t ).
- Use first kinematic equation of motion in both x and y directions.
- The accelerations ( ax and ay ) in the direction of each axis are to be determined. We know that the gravity acceleration ( g ) acts in vertical direction or along y-axis ( ay ) and always directed downwards while velocity is directed up. Since, we neglected the effects of air-resistance there is no acceleration in the x-direction ( ax = 0 ) .
- We see that the horizontal velocity of the ball ( vxf ) at any point in time remains equal to the initial horizontal velocity; hence, it is constant throughout the journey.
- However, the velocity of the ball in vertical direction( vyf ) is changing for every unit of time ( t ) under the influence of gravitational acceleration. Hence, it is not constant throughout the journey
Given that,
Mass of a water balloon, m = 1 kg
It comes downward an experience a 4.9 N air resistance as it approaches the ground.
To find,
The acceleration of the water balloon when it experiences this air resistance.
Solution,
Let the acceleration be a.
The net force acting on it will be :
The force is also given by :
F = ma
So, the acceleration of the water balloon is .
Answer:
distance travelled= 12 x 3=36 m