Answer:
P = 450 J
Explanation:
Given that,
Mass of a child, m = 18 kg
The vertical distance from the top to the bottom of the slide is 2.5 metres.
The Gravitational field strength = 10 N/kg
We need to find the decrease in gravitational potential energy of the child sliding from the top to the bottom of the slide.
The formula for the gravitational potential energy is given by :
P = mgh
Substituting all the values,
P = 18 kg × 10 m/s² × 2.5 m
P = 450 J
Hence, the decrease in gravitational potential energy is 450 J.
Answer:
20 Joules
Explanation:
Work is done whenever a force moves a body through a certain distance in the direction of the force. So, work done is the product of force and distance moved.
Therefore, we have;
Work done = Force x distance
i.e Wd = Fs
Given that: F = 20 N and s = 1 m, then;
Wd = 20 N x 1 m
= 20 Nm
The work done by the father is 20 Joules(Nm).
Answer:
Two equal and opposite parallel forces not acting along the same line, form a couple. A couple is always needed to produce the rotation.
For example, turning a key in a lock and turning a steering wheel.
Explanation:
It is given that,
An electron is released from rest in a weak electric field of, 
Vertical distance covered, 
We need to find the speed of the electron. Let its speed is v. Using third equation of motion as :
.............(1)
Electric force is 
and force of gravity is 
. As both forces are acting in downward direction. So, total force is:
Acceleration of the electron, 
Put the value of a in equation (1) as :
v = 0.010 m/s
So, the speed of the electron is 0.010 m/s. Hence, this is the required solution.
1. The balls move to the opposite direction but the same speed. This represents Newton's third law of motion.
2. The total momentum before and after the collision stays constant or is conserved.
3. If the masses were the same, the velocities of both balls after the collision would exchange.
4 and 5. Use momentum balance to solve for the final velocities.
