Dave runs a 400 m race with a speed of 4 m/s. What time will it take him to finish the race?

A ball is thrown straight up in the air. For which situations are both the instantaneous velocity and the acceleration zero? (Se

Gwar [14]

Answer:

Therefore, the situation in which both the instantaneous velocity and acceleration become zero, is the situation when the ball reaches the highest point of its motion.

Explanation:

When a ball is thrown upward under the free fall action of gravity, it starts to loose its Kinetic Energy as it moves upward. As the ball moves in upward direction, its kinetic energy gradually converts into its potential energy. As a result the speed of the ball starts to decrease as it moves up. Therefore, at the highest point during its motion, the velocity of ball becomes zero and it stops at the highest point for a moment, and then it starts to fall back down, under the influence of gravitational force.

Therefore, the situation in which both the instantaneous velocity and acceleration become zero, is the situation when the ball reaches the highest point of its motion.

6 0

2 years ago

Who exerts more pressure? a) A girl of 50 kg, wearing heels with an area of 1 cm2. b) An elephant of 4000 kg with foot area of 2

Mrrafil [7]

Answer:

The girl exerts more pressure.

Explanation:

Pressure can be defined as the force exerted normally or perpendicularly per unit area.

i.e P = F/A

Girls

Area of the heel = 1cm² = 10^(-4) m²

Force = mg = 50 × 10 = 500N

Pressure =

$\frac{500}{10 ^{ - 4} }$

$= 5 \times {10}^{6}$

Elephant

Area = 250cm² = 2.5 x 10^(-2)b m²

Force = mg = 40000N

Pressure =

$\frac{40000}{2.5 \times {10}^{ - 2} }$

$= 1.6 \times {10}^{6}$

5 0

2 years ago

Si un auto se mueve en rapidez constante de 25,0m/s a lo largo de 2500 m en línea recta, ¿cuál es la magnitud de la fuerza resul

Nataly_w [17]

Answer:

F= 0

Explanation:

This exercise we use Newton's second law,

F = m a

in this case as the speed is constant the acceleration is zero therefore the force is zero.

Change we can solve it using Newton's first law, which states that every vehicle remains still or with constant speed if there is no extensive outside acting on it

We see that with any of the two forms the sum of the applied forces is zero

∑ F = 0

3 0

2 years ago

A car of mass 1000 kg travelling at a velocity of 25 m/s collides with another car of mass 1500kg which is at rest. The two cars

Svetach [21]

Answer:

The velocity of the two cars is 10 m/s after the collision.

Explanation:

Law Of Conservation Of Linear Momentum

The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and velocity v is

P=m.v

If we have a system of bodies, then the total momentum is the sum of them all

$P=m_1v_1+m_2v_2+...+m_nv_n$