A soccer ball is rolling across a soccer field. The system consists of the

Name three forces involved in brushing your teeth.

Viefleur [7K]

Three forces involved in brushing your teeth are first push, then pull, then push.

3 0

3 years ago

Calculate the KE of a car which has a mass of 1000 kg and is moving at the rate of 20 m/s

Elan Coil [88]

Answer:

The kinetic energy of the car is $2.0\cdot 10^5 J$

Explanation:

3 0

2 years ago

A jogger runs by a river with a velocity of 7 m s relative to the ground. A leaf floating on the river moves with a velocity of

Hunter-Best [27]

Answer:

The velocity of the leaf relative to the jogger is 5 m/s.

Explanation:

Given that,

Velocity of jogger wrt to the ground, $V_j=7\ m/s$

velocity of leaf wrt the ground, $v_i=2\ m/s$

We need to find the velocity of the leaf relative to the jogger. Let it is equal to V. So, it is given by :

$V=v_j-v_i\\\\V=7-2\\\\V=5\ m/s$

So, the velocity of the leaf relative to the jogger is 5 m/s. Hence, this is the required solution.

3 0

4 years ago

A kangaroo can jump over an object 2.46 m high. (a) Calculate its vertical speed (in m/s) when it leaves the ground.

Elenna [48]

Answer:

a) 6.95 m/s

b) 1.42 seconds

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.81 m/s²

$v^2-u^2=2as\\\Rightarrow -u^2=2as-v^2\\\Rightarrow -u^2=2\times -9.81\times 2.46-0^2\\\Rightarrow u=\sqrt{2\times 9.81\times 2.46}\\\Rightarrow u=6.95\ m/s$

a) The vertical speed when it leaves the ground. is 6.95 m/s

$v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-6.95}{-9.81}\\\Rightarrow t=0.71\ s$

Time taken to reach the maximum height is 0.71 seconds

$s=ut+\frac{1}{2}at^2\\\Rightarrow 2.46=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{2.46\times 2}{9.81}}\\\Rightarrow t=0.71\ s$

Time taken to reach the ground from the maximum height is 0.71 seconds

b) Time it stayed in the air is 0.71+0.71 = 1.42 seconds

3 0

3 years ago

Why are the poles and slightly lower latitudes so cold in the summertime when they receive almost 24 hours of daylight? I know t

castortr0y [4]

Explanation:

As the earth travels around the sun in the elliptical orbit it must also be know that the axis of the earth is tilted as well.

So when the earth is at the farthest point and the tilt of the earth's axis is towards the sun in that case the sun rays always incident on the surface of the earth near the poles and hence there is sunlight for the 24 hours of the day. But the intensity of these rays is very low because of the their slanted angle of incident. In other words the same sun rays cover a larger area and the luminous intensity is reduced.

When the earth is near to the sun we have an increased average temperature of the day during that phase giving us an experience of summer season and vice-versa is the condition in winter seasons. The tilt of the earths axis is responsible for variation in extremities of the seasons with respect to the geographical location.

5 0

3 years ago