All categories

3 years ago

A ball thrown straight up climbs for 3.0 sec before falling. Neglecting air resistance, with what velocity was the ball thrown?

Physics

1 answer:

sesenic [268]3 years ago

7 0

Answer:

Speed, u = 29.4 m/s

Explanation:

Given that, A ball thrown straight up climbs for 3.0 sec before falling, t = 3 s

Let u is speed with which the ball is thrown up. When the ball falls, v = 0

Using first equation of motion as :

v = u + at

Here, a = -g

So, u = g × t

$u=9.8\times 3$

u = 29.4 m/s

So, the speed with which the ball was thrown is 29.4 m/s. Hence, this is the required solution.

You might be interested in

This equation is known as the ideal gas law, and it can be used to predict the behavior of many gases at relatively low pressure

Masja [62]

The correct answer is
<span>C) either the pressure of the gas, the volume of the gas, or both, will increase.

In fact, the ideal gas law can be written as
</span> $pV=nRT$
<span>where
p is the gas pressure
V is its volume
n is the number of moles
R is the gas constant
T is the absolute temperature of the gas

We can see that if the temperature T increases, then the term on the right in the equation increases, therefore the term on the left should increase as well. In order for this to be possible, at least one between p and V should increase, or also both of them. Therefore, the correct answer is C.</span>

6 0

3 years ago

Pumping of groundwater in California most effectively: Select one:

maria [59]

Answer:

Explanation:

Ans- A, causes sediments in aquifers that are emptied to compact and the ground above it to sink.

This is one of the major problems for California nowadays. Due to excessive groundwater pumping to satisfy the demand of huge population the aquifers are drying, hence compacting and for that the land above sinks.

7 0

3 years ago

The temperature of air changes from 0 to 10°C while its velocity changes from zero to a final velocity, and its elevation change

aliya0001 [1]

Answer:

Final velocity = 119.83 m/s

Final elevation = 731.9 m

Explanation:

We are told that temperature of air changes from 0 to 10°C

Thus;

Change in temperature; ΔT = 10 - 0 = 10°C

Also, its velocity changes from zero to a final velocity. Thus;

v1 = 0 m/s

v2 is unknown

Also, its elevation changes from zero to a final elevation.

So, z1 = 0 and z2 is unknown

Now, we want to find v2 and z2 when the internal, kinetic and potential energy are equal.

Thus Equating the formula for both kinetic and internal energy gives;

½m(v2² - v1²) = mc_v•ΔT

m will cancel out and v1 is zero to give;

v2² = 2c_v•ΔT

v2 = √(2c_v•ΔT)

Where c_v is specific heat of constant volume of air with a constant value of 718 J/Kg.K

Thus;

v2 = √(2 × 718 × 10)

v2 = √14360

v2 = 119.83 m/s

To find z2, we will equate potential energy formula to that of the internal energy.

Thus;

mg(z2 - z1) = mc_v•ΔT

m will cancel out and since z1 is zero, then we have;

z2 = (c_v•ΔT)/g

z2 = 718 × 10/9.81

z2 = 731.9 m

4 0

4 years ago

Reading the temperature of a solution by using a thermometer is an example of a(n) ________.

blsea [12.9K]

Answer:

B. Observation

Explanation:

Using a thermometer to read the temperature of a solution is tantamount to the making an observation.

Observation are recorded using our senses of sight, taste, earing, feeling etc or by the use of instrument.

Through observation, data is usually collected to make inferences about an experiment.
An observation leads to the formulation of a hypothesis which is scientific guess that leads to experimental designs.
Conclusions are drawn from the information of data obtained from an experiment.

4 0

3 years ago

The horizontal surface on which the block (mass 2.0 kg) slides is frictionless. The speed of the block before it touches the spr

ch4aika [34]

Answer:3.67 m/s

Explanation:

mass of block(m)=2 kg

Velocity of block=6 m/s

spring constant(k)=2 KN/m

Spring compression x=15 cm

Conserving Energy

energy lost by block =Gain in potential energy in spring