A man pushes(推) the pram（婴儿车） up. How much work done by the push force? (unit: J )
If the work done by the pram is 3000J, the total time for this process is 10s, What is the power of the pram? (unit:W)
A man pushes the 10kg pram up with an constant speed（匀速） which is 10m/s. What is the kinetic energy of the pram?
A man pushes the 10kg pram up. What is the change in gravitational potential energy of the pram?
Assume the useful energy is the change in g.e(重力势能), input energy is the work done by the push force. 请问他的效率为百分之多少？保留整数
A ball is released（释放） from rest(静止) and rolls downward（下滑）, Assume the mass of the ball is 1 kg, h=5 m. 在最高点时，小球拥有的能量如何分布。
重力势能最大，动能最小
重力势能最大，动能最大
重力势能最小，动能最小
重力势能最小，动能最大
重力势能和动能一样
A ball is released（释放） from rest(静止) and rolls downward（下滑）, Assume the mass of the ball is 1 kg, h=5 m. 如果不计空气阻力，请问在这个过程中能量如何进行转换？
重力势能全部转成动能
动能全部转成重力势能
重力势能转化为动能+内能
动能转化为重力势能+内能
A ball is released（释放） from rest(静止) and rolls downward（下滑）, Assume the mass of the ball is 1 kg, h=5 m. 当小球下滑到平面时，下列说法正确的是？
平面如果是光滑的，则小球做匀速直线运动
平面如果是光滑的，则小球会不断减速直到为0
平面如果是粗糙的，则小球会不断减速并最终反向运动
平面如果是粗糙的的，则小球做匀速直线运动
Assume mass of the ball is 1 kg, h=5 m. And the surface is smooth(光滑), what is the velocity when ball hits the block B? （空气阻力不计，单位：m/s）
Assume mass of the ball is 1 kg, h=5 m. And the surface is not smooth, 空气阻力不计,Assume the friction between the surface and ball is 10N, 请问这个球可以在平面上滑行多远？ (单位:m）
A matter is rigid and has fixed shape. What is the state of this matter? （首个字母不要大写）
A matter can be squashed. What is the state of this matter?
What can be infer from the figure below？
The mass of liquid is unchanged
The liquid has fixed shape
The liquid is not rigid
The liquid takes the shape of its container
The liquid can be squashed
What is the state of this matter for this graph?
What is the density of the liquid? (unit:g/cm3)
A matter's particle can only vibrate when temperature is increasing. What is the state of this matter?
Some gas has volume of 2 m3 at pressure of 1000pa. When the pressure increasing to 5000pa,What is new volume of the gas? (unit : m2)
When the piston is pushed to left, and the temperature is unchanged. What is pressure(P) and density(ρ) of the gas?
P decrease / ρ decrease
P increase / ρ increase
P increase / ρ decrease
P decrease / ρ increase
P increase / ρ unchanged
P decrease / ρ unchanged
This container has fixed volume. When the temperature is increasing. 1.分子运动速度 2. 分子撞墙频率 3. 分子撞墙的力 4. 分子动能 5. 分子重力势能 6. 分子密度。请问上述描述中一定增大的有几个？
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