Answer: A. Tennis ball hit into a net
Explanation:
Momentum = m.v (where m = mass of object and v = velocity of object)
However, the velocity of the ball is in a direction +x
The mass of the ball is definitely comstant. However, the ball's velocity is subject to change - both in magnitude and direction.
When the ball is hit at one side of the court, it assumes a velocity u.
Its momentum at u = m.u-->
(--> representing the direction)
Immediately it crashes into the net,both the magnitude and direction of its velocity experience a sharp change as it is hurled in a direction opposite its former direction.
Obviously, the correct answer is option A
A) Prevent (just imagine bushing a box up a ramp in your head)
Answer:
a. Bar A is a magnet
b. Bar B is a metal or magnetic material
c. Bar D is a non-magnetic material
Explanation:
a. Bar A
Since B attracts both A and C, it shows that A and C are both magnetic. So, it is either B and A are magnets or B and C are magnets or A and C are magnets. Also, since A and C sometime attract one another and sometimes repel one another, it means that they attract when their poles are opposite and repel when their poles are negative. This show that both A and C are magnets. Thus, A is a magnet.
b. Bar B
Since B is attracted to both A and C and we know that both A and C are magnets, it implies that B is a magnetic material. Since it does not repel either A or C.
c. Bar D
Since D does not attract A, B or C, D is a non-magnetic material. Since, only a magnetic material can be attracted to magnets and we have established that both A and C are magnets and that B is magnetic. Since D is not also attracted to B, it implies that D is thus non-magnetic.
Answer:
39.8 °C
Explanation:
m = mass of the ice = 100 g
L = latent heat of fusion of ice = 334 Jg⁻¹
M = mass of water = 200 g
= specific heat of water = 4.2 Jg⁻¹°C⁻¹
= initial temperature of water = ?
= final temperature of water = 0 °C
Using conservation of heat
Heat gained by ice = heat lost by water
m L = M ( - )
(100) (334) = (200) (4.2) ( - 0 )
= 39.8 °C